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당신은 주제를 찾고 있습니까 “sybase add column – Sybase Tutorial for Beginners : 2 Sybase Alter Table“? 다음 카테고리의 웹사이트 https://chewathai27.com/you 에서 귀하의 모든 질문에 답변해 드립니다: https://chewathai27.com/you/blog. 바로 아래에서 답을 찾을 수 있습니다. 작성자 r2schools 이(가) 작성한 기사에는 조회수 477회 및 좋아요 6개 개의 좋아요가 있습니다.

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d여기에서 Sybase Tutorial for Beginners : 2 Sybase Alter Table – sybase add column 주제에 대한 세부정보를 참조하세요

In this video, we have explained the Sybase alter table syntax, actions can be performed using Alter table command with examples.

sybase add column 주제에 대한 자세한 내용은 여기를 참조하세요.

Sybase Add Column to Sybase Database Tables via the Alter …

Information on how to add columns to Sybase database tables using the Sybase Alter Table Add Column command.

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Source: razorsql.com

Date Published: 9/7/2022

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Sybase add column – sql – Stack Overflow

I ran the following with no errors or warning, and the text field was appended to the table as expected: create table hello ( int) Alter …

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Source: stackoverflow.com

Date Published: 7/21/2021

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Column DEFAULT Clause – Sybase SQL Anywhere – SQLines

The DEFAULT clause allows you specifying the default value for a column. The default value is assigned if you omit the column or specify DEFAULT keyword in …

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Source: www.sqlines.com

Date Published: 11/14/2022

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Add Column to a table – sybase.ase.performance+tuning – CodeVerge

Hi, I woule like to add a non-null column to an existing fixed wth database table. Is there any performance difference between “alter table” an… 892987.

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how to add new column in the sybase IQ to the existing table …

Hi All, how to add new column in the sybase iq to the existing table(Column i am trying to add has to be in the first column in the table) …

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ALTER TABLE statement

Adding clauses The following section explains the clauses used for adding columns or table constraints to a table: ADD column-name [ AS ] column-data-type [ new …

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ALTER TABLE statement

add-clause Add a new column or table constraint to the table. … Sybase Some clauses are supported by Adaptive Server Enterprise.

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add column if it does not exist – narkive

If a column does not already exist on a table I want to add it. The … Error: com.sybase.jdbc3.jdbc. … Column name ‘Status’ in table ‘Person’ is

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주제와 관련된 더 많은 사진을 참조하십시오 Sybase Tutorial for Beginners : 2 Sybase Alter Table. 댓글에서 더 많은 관련 이미지를 보거나 필요한 경우 더 많은 관련 기사를 볼 수 있습니다.

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주제에 대한 기사 평가 sybase add column

• Author: r2schools
• Views: 조회수 477회
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• Date Published: 2019. 7. 25.
• Video Url link: https://www.youtube.com/watch?v=FlLU3-slDCM

How do I add a column in Sybase?

Use the alter table command to add a column to an existing table. Use alter table to drop a column from an existing table. Use alter table to modify an existing column. You can modify any number of columns in a single alter table statement.

How do I drop a column in Sybase?

The RazorSQL alter table tool includes a Drop Column option for dropping a column from a Sybase database table. The drop column function allows the user to select a column to drop from the table. The tool then generates the appropriate alter table drop column SQL command for dropping the column from the table.

How do I rename a column in Sybase?

How do you add a column to the middle in Oracle?

By default, columns are only added at the end. To insert a column in the middle, you have to drop and recreate the table and all related objects (constraints, indices, defaults, relationships, etc). Several tools do this for you, and depending on the size of the table, this may be an intensive operation.

How do I edit a column in SQL?

How do you name a column in SQL?

You select the table with ALTER TABLE table_name and then write which column to rename and what to rename it to with RENAME COLUMN old_name TO new_name .

How do I delete a column in a database?

In Object Explorer, connect to an instance of Database Engine. In Object Explorer, locate the table from which you want to delete columns, and expand to expose the column names. Right-click the column that you want to delete, and choose Delete. In Delete Object dialog box, click OK.

How do I drop an index in Sybase?

To drop such indexes, drop the constraints through alter table or drop the table. See create table for more information about unique constraint indexes. You cannot drop indexes that are currently used by any open cursor. For information about which cursors are open and what indexes they use, use sp_cursorinfo.

How do I change primary key in Sybase?

How do you change a column name?

To change a column name, enter the following statement in your MySQL shell: ALTER TABLE table_name RENAME COLUMN old_column_name TO new_column_name; Replace table_name , old_column_name , and new_column_name with your table and column names.

How can I change column name in SQL Server?

How do you rename a value in SQL?

First, specify the table name that you want to change data in the UPDATE clause. Second, assign a new value for the column that you want to update. In case you want to update data in multiple columns, each column = value pair is separated by a comma (,). Third, specify which rows you want to update in the WHERE clause.

How do I add a column to a table in SQL Developer?

First, you specify the name of the table, which you want to add the new column, after the ALTER TABLE clause. Second, you specify the column name, data type, and its constraint.

How do I add a column to a table at a specific position in Oracle?

There is no command to “alter table add column at position 2”; Oracle simply places the column after all the existing columns. Technically speaking, the column order is unimportant. A relational database is about sets, and in sets the order of attributes and tuples does not matter.

Can we add a column to a table at the beginning of the table?

There is no ALTER statement you can run that will insert it at the beginning.

How do I add a column to a specific position in SQL Server?

How do I change the order of columns in Oracle SQL Developer?

How do you drop a column from a table in Oracle?

To physically drop a column you can use one of the following syntaxes, depending on whether you wish to drop a single or multiple columns. alter table table_name drop column column_name; alter table table_name drop (column_name1, column_name2);

How do I add more columns in MySQL?

The syntax to add a column in a table in MySQL (using the ALTER TABLE statement) is: ALTER TABLE table_name ADD new_column_name column_definition [ FIRST | AFTER column_name ]; table_name.

Sybase Add Column to Sybase Database Tables via the Alter Table Command

Sybase Alter Table Add Column

The RazorSQL alter table tool includes an Add Column option for adding columns to Sybase database tables. The add column function has options for the new column name, the new column data type, the size and scale of the new type, whether or not the new column should allow null values, and whether or not the new column has a default value associated with it.

Listed below are examples of the SQL generated by the Sybase Alter Table Add Column function:

ALTER TABLE sample.dbo.employee ADD new_col char(25) ALTER TABLE sample.dbo.employee ADD new_col char(25) DEFAULT ’22’ NOT NULL

Below is a screen shot of the add column function of the Sybase alter table tool.

Alter Existing Tables

Use the alter table command to change the structure of an existing table.

Add columns and constraints

Change column default values

Add NULL and NOT NULL columns

Drop columns and constraints

Change the locking scheme

Partition or unpartition tables

Convert column datatypes

Convert the null default value of existing columns

Increase or decrease column length You can:

You can also change a table’s partitioning attributes.

For example, by default, the au_lname column of the authors table uses a varchar(50) datatype. To alter the au_lname to use a varchar(60) , enter:

alter table authors modify au_lname varchar(60)

Note: You cannot use a variable as the argument to a default that is part of an alter table statement.

Dropping, modifying, and adding non-null columns may perform a data copy, which has implications for required space and the locking scheme.

The modified table’s page chains inherits the table’s current configuration options (for example, if fillfactor is set to 50 percent, the new pages use the same fillfactor).

Note: SAP ASE performs partial logging (of page allocations) for alter table operations. However, because alter table is performed as a transaction, you cannot dump the transaction log after running alter table ; you must dump the database to ensure it is recoverable. If the server encounters any problems during the alter table operation, SAP ASE rolls back the transaction.

alter table acquires an exclusive table lock while it is modifying the table schema. This lock is released as soon as the command has finished.

alter table does not fire any triggers.

Sybase Drop Column from a Sybase Database Table via the Alter Table Command

Sybase Alter Table Drop Column

The RazorSQL alter table tool includes a Drop Column option for dropping a column from a Sybase database table. The drop column function allows the user to select a column to drop from the table. The tool then generates the appropriate alter table drop column SQL command for dropping the column from the table.

Listed below is an example of the SQL generated by the Sybase Alter Table Drop Column function:

ALTER TABLE sample.dbo.employee DROP ssn

Below is a screen shot of the drop column function of the Sybase alter table tool.

rename

Chapter 1: System Procedures

Description

Changes the name of a user-created object or user-defined datatype in the current database.

Syntax

sp_rename objname, newname [,“index” | “column”]

Parameters

objname is the original name of the user-created object (table, view, column, stored procedure, index, trigger, default, rule, check constraint, referential constraint, or user-defined datatype). If the object to be renamed is a column in a table, objname must be in the form “table.column”. If the object is an index, objname must be in the form “table.indexname”.

newname is the new name of the object or datatype. The name must conform to the rules for identifiers and must be unique to the current database.

index specifies that the object you are renaming is an index, not a column. This argument allows you to rename an index that has the same name as a column, without dropping and re-creating the index.

column specifies that the object you are renaming is a column, not an index. This argument is part of the same option as the index argument.

Examples

Example 1

Renames the titles table to books:

sp_rename titles, books

Example 2

Renames the title column in the books table to bookname:

sp_rename “books.title”, bookname

Example 3

Renames the titleind index in the books table to titleindex:

sp_rename “books.titleind”, titleindex

Example 4

Renames the user-defined datatype tid to bookid:

sp_rename tid, bookid

Example 5

Renames the title_id index in the titles table to isbn:

sp_rename “titles.title_id”, isbn, “index”

Usage

sp_rename changes the name of a user-created object or datatype. You can change only the name of an object or datatype in the database in which you issue sp_rename .

When you are renaming a column or index, do not specify the table name in newname . See Examples 2, 3, and 5.

If a column and an index have the same name, use the [,“ index ” | “ column ”] argument, which specifies whether to rename the index or the column. In the following sample, assume that both an index and a column named idx exist: sp_rename “t.idx”, new_idx, “column” ————- Column name has been changed. (Return status = 0) sp_rename “t.idx”, new_idx, “index” ————- Index name has been changed. (Return status = 0)

If you change the name of a an object or column name referenced by a view, you see a warning message, such as: Changing an object or column name could break existing stored procedures, cached statements or other compiled objects.

You cannot change the names of system objects and system datatypes. WARNING! Procedures, triggers, and views that depend on an object whose name has been changed will no longer work. Change the definitions of any dependent objects before you execute sp_rename. Find dependent objects with sp_depends.

Permissions

Only the Database Owner or a System Administrator can use the setuser command to assume another database user’s identity to rename objects owned by other users. All users can execute sp_rename to rename their own objects.

Auditing

Values in event and extrainfo columns from the sysaudits table are:

Event Audit option Command or access audited Information in extrainfo 38 exec_procedure Execution of a procedure Roles – Current active roles

Keywords or options – NULL

Previous value – NULL

Current value – NULL

Other information – All input parameters

Proxy information – Original login name, if set proxy in effect

See also

System procedures sp_depends, sp_rename

Inserting new columns in the middle of a table?

When one uses “ALTER TABLE tab ADD col”, the new column gets added to the end of the table. For example:

TABLE: TAB COL_1 COL_2 COL_4 ALTER TABLE TAB ADD COL_3

table will become

TABLE: TAB COL_1 COL_2 COL_4 COL_3

However as the naming of my example columns suggests I’d actually like the table to end up like this:

TABLE: TAB COL_1 COL_2 COL_3 COL_4

With COL_3 before COL_4.

Besides rebuilding the table from scratch, is there any standard SQL that will get the job done? However if there is no standard SQL, I could still use some vendor dependent solutions for Oracle, but again a standard solution would be best.

Thanks.

Sybase add column

I am trying to add column with text datatype with below query in Sybase

Alter table table-name Add column-name text NULL

it throws error : row size could exceed row size limit, which is 1964 bytes

Please suggest appropriate query

Column DEFAULT Clause

— Insert NULL, not default (!) to name column

— Insert default values to all columns

— Insert default value ‘N/A’ to name column

The DEFAULT clause allows you specifying the default value for a column. The default value is assigned if you omit the column or specify DEFAULT keyword in a INSERT statement.

Last Update: Sybase SQL Anywhere 12.0

You can specify a string literal, numeric value or datetime literal as well as functions and expressions as the default value for a column:

CREATE TABLE products ( name VARCHAR ( 80 ) NOT NULL DEFAULT ‘N/A’ , category VARCHAR ( 80 ) NULL DEFAULT ‘Not Defined’ , created TIMESTAMP DEFAULT CURRENT TIMESTAMP , expiry TIMESTAMP DEFAULT DATEADD ( month , 1 , CURRENT TIMESTAMP ) , price MONEY DEFAULT 0 ) ;

You can use DEFAULT VALUES keyword to insert default values to all columns:

INSERT INTO products DEFAULT VALUES ;

To insert the default value for a specified column, you can omit it or specify DEFAULT keyword in INSERT statement:

— Insert default values for category, created and expiry columns INSERT INTO products ( name , price ) VALUES ( ‘Apple’ , 1 . 29 ) ; — or INSERT INTO products VALUES ( ‘Orange’ , DEFAULT , DEFAULT , DEFAULT , 1 . 39 ) ;

Specifying NULL values does not assign default values:

— Column name is defined as NOT NULL, so the insert fails INSERT INTO products ( name ) VALUES ( NULL ) ; — Could not execute statement. — Column ‘name’ in table ‘products’ cannot be NULL — SQLCODE=-195, ODBC 3 State=”23000″ — Column category allows NULLs, so NULL is inserted INSERT INTO products ( category ) VALUES ( NULL ) ;

Table content:

sybase.ase.performance+tuning

Hi, I’m trying to create a GUID autogenerated column within my table using the Alter Table Add column Auery as shown below, ALTER TABLE MainTable ADD COLUMN [My_Guid] AUTOINCREMENT(Replication ID) Any help would be greatly appreciated.. Thanks, Acces doesn’t have a GUID data type. If you want to have GUID as Key field, you should use a Text Field, and you should fill it using code. If you want to have a autogenerated Primary Key, use [COUNTER], which will generate a Long value. Hi, Access has a AutoNumber Replcate ID type which is exactly…Hi, The following sp should insert the value read from a table but instead adds the literal “column_name”. How do I add what is in variable “column_name”? begin declare cur_employee dynamic scroll cursor for select column1 from temp_table; declare column_name char(40); open cur_employee with hold; loop fetch next cur_employee into column_name; alter table DBA.TEMP_ACCTING_TABLE add column_name varchar(40) null end loop; close cur_employee end TIA Lisa Change your ALTER TABLE command to : execute immediate ‘alter t…I want to add a column to every table in my AppModeler model. The column will be of the same name and type in all tables. I have about 200 tables, so I really don’t want to have to do this manually. Is there any way I can get AppModeler to do this for me automatically? Even if it’s only in the generated SQL scripts and not physically in the model, that would be fine. Thanks, Jamie Burks Unfortunately, there isn’t a function to add columns in this manner. Work arounds include: 1. Create the column in the first table, highlight the line in the column list and p…Everytime I click on a button I want to add a tableRow to a table like this: TextBox TB = new TextBox(); TableCell Cell = new TableCell(); Cell.Controls.Add(TB); TableRow Row = new TableRow(); Row.Cells.Add(Cell); table.Rows.Add(Row);It works the first time, but when I click the button again the last r…Hi, is there a sql command to add a column to a table which has been created? Thanks, Natalie >Hi, is there a sql command to add a column to a table which has been >created? Yes, e.g., alter table mytable add mynewcolumn integer; Leo Tohill – Team Sybase >> Please post in newsgroup, not via email << Useful links: Downloads: http://www.sybase.com/developer/mobile/ Submit Bug Reports: http://casexpress.sybase.com/cx/cx.stm?starturl=casemessage.ssc?CASETYPE=Bug ...Hello, We use ALTER TABLE to add a new column to a table with about 25 million rows. This takes a long time and after about 3 hours it fails saying that it has run out of locks with an error code of C210. If anyone can help me, I would really appreciate it. TIA Regards, Mahesh Please show us the ALTER TABLE that is failing. We may be able to suggest an alternative ALTER TABLE followed by a cursor update loop where you can do periodic COMMITs. The problem is that ALTER TABLE will do all it's work in one transaction and acquire too many locks. If you had a page size of 8...Hello there!, First of all i have two tables . one acts as a master table and other one acts as a details table. Currently the ptoblem with my procedure is, i have entered two entries for one project in the Master table. and to briefly discribe those two entries in the master table , i have entered two entries in the Details table corresponding to the entries in the master table. Now i need to combine the master table entries and the details table entries for the same project which should give only two entreies. but my procedure gives four entries. Could yo...I have 2 tables in a DataSet and have a link on them. I intend to put one column's content in one table, let's say t1, as the other column's link in the other table, let's say t2. However, after the link is created what I got is the t2's string in the link not the t1's. Here is my code: In the aspx: DataNavigateUrlFormatString="http://someweb.com/site/{0}" In the VB:'Create the link variableDim link As System.Web.UI.WebControls.HyperLinklink = DirectCast(e.Item.Cells(1).Controls(0), System.Web.UI.WebControls.HyperLink) 'Binding the link onto the column of Agency NameDim dr As Da...I have a CVdetails table which all the personal and technical details along with the path called CV_Path which stores the path of CV word doc. Using Index Server Query i got the paths in my SQL server using Linked Server. I used this Query SELECT Path FROM OPENQUERY (FileSystem,'SELECT Directory, FileName, DocAuthor, Size, Create, Write, Path FROM SCOPE ('' "c:\myCatalogFolder" '') WHERE FREETEXT (‘’reference’’)’) Which gave a result as Path c:\mycatalogfolder\ajaxguide.doc c:\mycatalogfolder\quickguide.txt Now,...I have a table that contains a column that is not null of a certain size. When altering that column to a different size as a not null value, I am required to use the default "some desc" option prior to the not null. ie: alter table table_name add column_name datatype DEFAULT "some name" not null. When I execute the sp_help table_name, I notice the column Default Name for the added column reflects an abreviation of the table and column name with some number. Is there away to issue the alter add column command on a table without the default option for a not n...Hi,I have one main table and multiple smaller tables, the main table consists of all the information gathered from the smaller tables, plus some other data. I've set primary keys for all the smaller tables and created a relationship where the primary key id matches an id field inside the main table eg. there's a smalltableid column in both the smaller table and the main table.some misc info:i'm using a dataset (should the key in the dataset be pointing to the main table, or the smaller one?)both relation and foreign key constraints are created (with no rules set)my problem is, the data from ...Have you already seen an 'ALTER TABLE ADD COLUMN NOT NULL" causing a corruption in the clustered index ? Is there some correction for this problem or is it better do not use 'alter table' in some cases ? tks! Adriano, Alberth wrote: > > Have you already seen an ‘ALTER TABLE ADD COLUMN NOT NULL” > causing a corruption in the clustered index ? Is there some > correction for this problem or is it better do not use > ‘alter table’ in some cases ? > > tks! CR 323730, fixed in 12.5.1 ESD #1 and 12.0.0.8: An ALTER TAB…Hi! i know “alert table tt add column aa varchar(20)” can add a new column named aa into table tt, but it’s not enough, i want to add columns named textbox.text into the table. i tried this: —————————————————————————————————— Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim myConnection As SqlConnection = New SqlConnection(ConfigurationSettings.AppSettings(“ConnectionString”)) myConnection.Open() D…I need to add some columns to an existing table, some need to be in the beginning of the table, some in between other columns and some at the end of the table. I am using SQL 2005 Enterprise. Thank you LadyDeeDarlene D. [email protected] Are you wanting to do this in code or the management Studio? In code, the only way is to put the data in a temporary location, drop the table, create the table with the new layout and then repopulate it from the temp storage. Can I ask why the fields need to be placed in a specific order? I mean you can reorder the fields a…

how to add new column in the sybase IQ to the existing table(Column i am trying to add has to be in the first column in the table)

Hi All,

how to add new column in the sybase iq to the existing table(Column i am trying to add has to be in the first column in the table)

Please advice!!

Thanks,

Aparna

ALTER TABLE statement

ASA SQL Reference

SQL Statements

ALTER TABLE statement

Description

Use this statement to modify a table definition or to enable a table to take part in Replication Server replication.

Syntax 1

ALTER TABLE [ owner.]table-name

{ add-clause | modify-clause | drop-clause | rename-clause }

add-clause :

ADD { column-definition | table-constraint }

| { ADD PCTFREE integer | PCTFREE DEFAULT }

modify-clause :

MODIFY column-definition

| MODIFY column-name { DEFAULT default-value

| [ NOT ] NULL

| [ CONSTRAINT constraint-name ]

CHECK { NULL | ( new-condition ) } }

| ALTER column-name column-modification

| ALTER constraint-name CHECK ( new-condition )

drop-clause :

{ DELETE | DROP }{

column-name

| CONSTRAINT constraint-name

| CHECK

| UNIQUE ( column-name, … )

| PRIMARY KEY

| FOREIGN KEY role-name }

rename-clause :

RENAME new-table-name

| RENAME column-name TO new-column-name

| RENAME constraint-name TO new-constraint-name

column-definition :

column-name data-type [ NOT NULL ] [ DEFAULT default-value ] [ column-constraint … ]

table-constraint :

[ CONSTRAINT constraint-name ] { UNIQUE ( column-name, … )

| PRIMARY KEY [ CLUSTERED ] ( column-name, … )

| foreign-key-constraint

| CHECK ( condition ) }

column-constraint :

[ CONSTRAINT constraint-name ] { UNIQUE

| PRIMARY KEY

| REFERENCES table-name

[ ( column-name ) ] [ actions ] [ CLUSTERED ]

| CHECK ( condition ) }

| COMPUTE ( expression )

column-modification :

SET DEFAULT default-value

| DROP DEFAULT

| ADD [ CONSTRAINT column-constraint-name ] CHECK ( condition )

| { DELETE | DROP } CONSTRAINT column-constraint-name

| { DELETE | DROP } CHECK

| SET COMPUTE ( expression )

| DROP COMPUTE

default-value :

special-value

| string

| global variable

| [ – ] number

| ( constant-expression )

| built-in-function( constant-expression )

| AUTOINCREMENT

| GLOBAL AUTOINCREMENT [ ( partition-size ) ]

| NULL

| TIMESTAMP

| UTC TIMESTAMP

| LAST USER

| USER

special-value:

CURRENT { DATABASE | DATE

| REMOTE USER | TIME

| TIMESTAMP | UTC TIMESTAMP

| USER | PUBLISHER }

foreign-key-constraint :

[ NOT NULL ] FOREIGN KEY [ role-name ] [ (column-name, … ) ]

REFERENCES table-name [ (column-name, … ) ] [ CLUSTERED ] [ actions ] [ CHECK ON COMMIT ]

actions :

[ ON UPDATE action ] [ ON DELETE action ]

action :

CASCADE | SET NULL | SET DEFAULT | RESTRICT

Syntax 2

ALTER TABLE [ owner.]table-name REPLICATE { ON | OFF }

Parameters

add-clause Add a new column or table constraint to the table. For more information, see below.

modify-clause Change a single column definition. For more information, see below.

drop-clause Drop a column or a table constraint. For more information, see below.

rename-clause Change the name of the table, a column, or a constraint. For more information, see below.

ADD column-definition Add a new column to the table.

If the column has a default value, all rows of the new column are populated with that default value.

Adaptive Server Anywhere optimizes the creation of columns that are allowed to contain NULL. The first column allowed to contain NULL allocates room for eight such columns, and initializes all eight to be NULL. (This requires no extra storage.) Thus, the next seven columns added require no changes to the rows of the table. Adding a ninth column then allocates room for another eight such columns and modifies each row of the table to allocate the extra space.

ADD table-constraint Add a constraint to the table. See CREATE TABLE statement for a full explanation of table constraints.

If PRIMARY KEY is specified, the table must not already have a primary key that was created by the CREATE TABLE statement or another ALTER TABLE statement.

The optional constraint name allows you to modify or drop individual constraints at a later time, rather than having to modify the entire table constraint.

Table CHECK constraints fail only if a value of FALSE is returned. A value of UNKNOWN allows the change.

PCTFREE Specify the percentage of free space you want to reserve for each table page. The free space is used if rows increase in size when the data is updated. If there is no free space in a table page, every increase in the size of a row on that page requires the row to be split across multiple table pages, causing row fragmentation and possible performance degradation.

A free space percentage of 0 specifies that no free space is to be left on each page—each page is to be fully packed. A high free space percentage causes each row to be inserted into a page by itself. If PCTFREE is not set, or if DEFAULT is specified, 200 bytes are reserved in each page.

When PCTFREE is set, all subsequent inserts into table pages use the new value, but rows that were already inserted are not affected. The value persists until it is changed or the table is dropped.

The PCTFREE specification can be used for base, global temporary, or local temporary tables. Except for local temporary tables, the value for PCTFREE is stored in the SYSATTRIBUTE system table.

For more information, see SYSATTRIBUTE system table.

MODIFY column-definition Change the length or data type of an existing column in a table. If NOT NULL is specified, a NOT NULL constraint is added to the named column. Otherwise, the NOT NULL constraint for the column will not be changed. If necessary, the data in the modified column will be converted to the new data type. If a conversion error occurs, the operation will fail and the table will be left unchanged.

You cannot modify a column to make it a computed column. Computed columns can only be added or dropped.

Deleting an index, constraint, or key If the column is contained in a uniqueness constraint, a foreign key, or a primary key, then the constraint or key must be deleted before the column can be modified. If a primary key is deleted, all foreign keys referencing the table will also be deleted. You cannot MODIFY a table or column constraint. To change a constraint, you must DELETE the old constraint and ADD the new constraint.

MODIFY column-name DEFAULT default-value Change the default value of an existing column in a table. To remove a default value for a column, specify DEFAULT NULL. Modifying a default value does not change any existing values in the table.

ALTER column-name column-modification Change the definition of a column. The permitted modifications are as follows:

SET DEFAULT default-value Change the default value of an existing column in a table. You can also use the MODIFY clause for this task, but ALTER is SQL/92 compliant, and MODIFY is not. Modifying a default value does not change any existing values in the table.

DROP DEFAULT Remove the default value of an existing column in a table. You can also use the MODIFY clause for this task, but ALTER is SQL/92 compliant, and MODIFY is not. Dropping a default does not change any existing values in the table.

ADD Add a named constraint or a CHECK condition to the column. The new constraint or condition applies only to operations on the table after its definition. The existing values in the table are not validated to confirm that they satisfy the new constraint or condition.

CONSTRAINT column-constraint-name The optional column constraint name allows you to modify or drop individual constraints at a later time, rather than having to modify the entire column constraint.

SET COMPUTE (expression) Change the expression associated with a computed column. The values in the column are recalculated when the statement is executed, and the statement fails if the new expression is invalid.

DROP COMPUTE Change a column from being a computed column to being a non-computed column. This statement does not change any existing values in the table.

MODIFY column-name [ NOT ] NULL Change the NOT NULL constraint on the column to allow or disallow NULL values in the column.

MODIFY column-name CHECK NULL Delete the check constraint for the column. This statement cannot be used on databases created before version 5.0.

MODIFY column-name CHECK (condition) Replace the existing CHECK condition for the column with the one specified. This statement cannot be used on databases created before version 5.0.

DELETE column-name Delete the column from the table. If the column is contained in any index, uniqueness constraint, foreign key, or primary key then the index, constraint, or key must be deleted before the column can be deleted. This does not delete CHECK constraints that refer to the column.

DELETE constraint-name Delete the named constraint from the table definition.

DELETE CHECK Delete all check constraints for the table. This includes both table check constraints and column check constraints.

DELETE UNIQUE (column-name, …) Delete a uniqueness constraint for this table. Any foreign keys referencing this uniqueness constraint (rather than the primary key) will also be deleted.

DELETE PRIMARY KEY Delete the primary key constraint for this table. All foreign keys referencing the primary key for this table will also be deleted.

DELETE FOREIGN KEY role-name Delete the foreign key constraint for this table with the given role name.

RENAME new-table-name Change the name of the table to new-table-name. Note that any applications using the old table name must be modified. Foreign keys that were automatically assigned the old table name will not change names.

RENAME column-name TO new-column-name Change the name of the column to the new-column-name. Note that any applications using the old column name will need to be modified.

Usage

Syntax 1 The ALTER TABLE statement changes table attributes (column definitions, constraints) in a table that was previously created. Note that the syntax allows a list of alter clauses; however, only one table-constraint or column-constraint can be added, modified or deleted in one ALTER TABLE statement. A table cannot be both added and modified in the same statement.

You cannot use ALTER TABLE on a local temporary table.

ALTER TABLE is prevented whenever the statement affects a table that is currently being used by another connection. ALTER TABLE can be time-consuming, and the server will not process requests referencing the table while the statement is being processed.

For more information on using the CLUSTERED option, see Using clustered indexes.

Before version 5.0, all table and column constraints were held in a single table constraint. Consequently, for these databases individual constraints on columns cannot be deleted using the MODIFY column-name CHECK NULL clause or replaced using the MODIFY column-name CHECK (condition ) clause. To use these statements, the entire table constraint should be deleted and the constraints added back using the MODIFY column-name CHECK (condition ) clause. At this point you can use MODIFY CHECK.

Syntax 2 When a table has REPLICATE ON, all changes to the table are sent to Replication Server for replication. The replication definitions in Replication Server are used to decide which table changes are sent to other sites. The remainder of this section describes syntax 1.

Permissions

Must be one of the following:

The owner of the table.

A user with DBA authority.

A user granted ALTER permission on the table.

ALTER TABLE requires exclusive access to the table.

Global temporary tables cannot be altered unless all users that have referenced the temporary table have disconnected.

Side effects

Automatic commit.

The MODIFY and DELETE (DROP) options close all cursors for the current connection.

A checkpoint is carried out at the beginning of the ALTER TABLE operation.

Once you alter a column or table, any stored procedures, views or other items that refer to the altered column no longer work.

See also

CREATE TABLE statement

DROP statement

SQL Data Types

Altering tables

Special values

Using table and column constraints

Standards and compatibility

SQL/92 Intermediate-level feature. MODIFY is not SQL/92 compliant.

SQL/99 ADD COLUMN is a core feature. Other clauses are vendor extensions or implementation of specific, named extensions to SQL/99.

Sybase Some clauses are supported by Adaptive Server Enterprise.

Example

The following example adds a new column to the employee table showing which office they work in.

ALTER TABLE employee ADD office CHAR(20) DEFAULT ‘Boston’

The following example drops the office column from the employee table.

ALTER TABLE employee DELETE office

The address column in the customer table can currently hold up to 35 characters. To allow it to hold up to 50 character, type the following.

ALTER TABLE customer MODIFY address CHAR(50)

The following example adds a column to the customer table assigning each customer a sales contact.

ALTER TABLE customer ADD sales_contact INTEGER REFERENCES employee (emp_id) ON UPDATE CASCADE ON DELETE SET NULL

This foreign key is constructed with cascading updates and is set null on deletes. If an employee has their employee ID changed, the column is updated to reflect this change. If an employee leaves the company and has their employee ID deleted, the column is set to NULL.

add column if it does not exist

Post by a***@gmail.com

If a column does not already exist on a table I want to add it. The

column already exists in the database I am testing this in.

IF NOT EXISTS(SELECT 1

FROM sysobjects,

syscolumns

WHERE sysobjects.id = syscolumns.id

AND sysobjects.name = ‘Person’

AND syscolumns.name = ‘Status’)

BEGIN

ALTER TABLE Person

ADD Status char(1)

DEFAULT ‘E’ NOT NULL

END

Error: com.sybase.jdbc3.jdbc.SybSQLException: Column names in each

table must be unique. Column name ‘Status’ in table ‘Person’ is

specified more than once.

, SQL State: ZZZZZ, Error Code: 2705

However

IF NOT EXISTS(SELECT 1

FROM sysobjects,

syscolumns

WHERE sysobjects.id = syscolumns.id

AND sysobjects.name = ‘Person’

AND syscolumns.name = ‘Status’)

BEGIN

ALTER TABLE Person

ADD Status char(1) NULL

END

Query 1 of 1 elapsed time (seconds) – Total: 0, SQL query: 0, Building

output: 0 (success)

If a column does not already exist on a table I want to add it. Thecolumn already exists in the database I am testing this in.IF NOT EXISTS(SELECT 1FROM sysobjects,syscolumnsWHERE sysobjects.id = syscolumns.idAND sysobjects.name = ‘Person’AND syscolumns.name = ‘Status’)BEGINALTER TABLE PersonADD Status char(1)DEFAULT ‘E’ NOT NULLENDError: com.sybase.jdbc3.jdbc.SybSQLException: Column names in eachtable must be unique. Column name ‘Status’ in table ‘Person’ isspecified more than once., SQL State: ZZZZZ, Error Code: 2705HoweverIF NOT EXISTS(SELECT 1FROM sysobjects,syscolumnsWHERE sysobjects.id = syscolumns.idAND sysobjects.name = ‘Person’AND syscolumns.name = ‘Status’)BEGINALTER TABLE PersonADD Status char(1) NULLENDQuery 1 of 1 elapsed time (seconds) – Total: 0, SQL query: 0, Buildingoutput: 0 (success)

Your solution would be to use dynamic SQL for the DDL. The error isbeing raised during normalizations (as the parse tree is beingconverted into a normalized query tree) rather than at execution. Thecontents of dynamic sql aren’t processed until they are actuallycalled, avoiding the error.IF NOT EXISTS(SELECT 1FROM sysobjects,syscolumnsWHERE sysobjects.id = syscolumns.idAND sysobjects.name = ‘Person’AND syscolumns.name = ‘Status’)BEGINEXECUTE (” ALTER TABLE PersonADD Status char(1)DEFAULT ‘E’ NOT NULL”)END

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