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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
Add, Drop, or Modify Columns with User-Defined Datatypes...
- 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...
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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)
ALTER [COLUMN] is SQL feature F381, as is the ability to add, modify, or drop a DEFAULT value for a column. In SQL/2008, altering the data type of a column is performed by specifying the SET DATA TYPE clause, which is SQL language feature F382.
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.
Changes a virtual computed column to a materialized computed column: alter table authors modify fullname materialized Usage. Before you add, modify, or drop columns on a table, run the sp_depends stored procedure to see if there are any stored procedures that depend on the table you are changing. If such stored procedures exist, Sybase ...
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