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The ALTER TABLE statement changes table attributes (column definitions and constraints) in a table that was previously created. The syntax allows a list of alter clauses; however, only one table constraint or column constraint can be added, modified, or deleted in each ALTER TABLE statement.
- SyBooks Online
Errors and Warnings Generated by alter table modify Scripts...
- Identity_Insert Option
A table name must be specified to identify the column to...
- Alter User Statement
ALTER USER statement Description. Changes user settings....
- Create Table Statement
CREATE TABLE statement Description. Creates a new table in...
- Alter Service Statement
Otherwise, the specified SQL statement is the only one that...
- Modify Columns
Use alter table to modify an existing column. You can modify...
- SyBooks Online
Use alter table to modify an existing column. You can modify any number of columns in a single alter table statement. For example, this command changes the datatype of the type column in the titles table from char(12) to varchar(20) and makes it nullable:
28 Ιουν 2012 · To alter any table in order to change the datatype of some field : ALTER TABLE <table_name> MODIFY <column_name> <new_datatype>. For example: In order to change the datatype of any column 'emp_id' from int to varchar, you need to : ALTER TABLE employee MODIFY emp_id varchar(10)
The ALTER TABLE statement changes table attributes (column definitions, constraints, and so on) in an existing table. The database server keeps track of object dependencies in the database. Alterations to the schema of a table may impact dependent views.
What is the most efficient way to alter a column definition in a table with millions of rows. and . ALTER TABLE on a large table with an indexed column. My current strategy is . Drop all non clustered index ; Drop clustered index; Alter table modifcy column varchar (32) -- column is char(20) presently; Recreate clustered index; recreate non ...
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.
Modifies a table definition. Syntax. ALTER TABLE [ owner .] table-name . { ADD column-definition [ column-constraint ]... | ADD table-constraint . | MODIFY column-definition . | MODIFY column-name [ IDENTITY ] [ DEFAULT AUTOINCREMENT ] [ NOT ] NULL . | MODIFY column-name [ CONSTRAINT constraint-name ] CHECK NULL .
