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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
Objects Using select * Do Not List Changes to Table Use...
- 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...
- alter table
adds or drops a new computed column. Follow the same rules...
- SyBooks Online
Transact-SQL ALTER TABLE is supported by Adaptive Server Enterprise. Adaptive Server Enterprise supports the ADD COLUMN and DROP COLUMN clauses, in addition to ADD CONSTRAINT and DROP CONSTRAINT. Adaptive Server Enterprise uses MODIFY rather than the keyword ALTER for the ALTER clause.
19 Αυγ 2013 · You can also add columns to existing tables by using the alter table command. For example, to add two new int columns to mytable_Audit, one with a default value, and the other as NULL: alter table mytable_Audit add col1 int default 0, col2 int NULL. answered Aug 21, 2013 at 1:13. Mike Gardner. 6,651 5 25 34. 0.
adds or drops a new computed column. Follow the same rules defined for the existing create table command and the alter table add rules. computed_column_expression. is any valid T-SQL expression that does not contain columns from other tables, local variables, aggregate functions, or subqueries.
You can add any number of columns using a single alter table statement. For example, the following adds a non-null column named author_type, which includes the constant “primary_author” as the default value, and a null column named au_publisher to the authors table: alter table authors. add author_type varchar(20) default "primary_author" not null,
ADD COLUMN statement as follows: ALTER TABLE table_name. ADD COLUMN new_column_name data_type . [FIRST | AFTER existing_column]; Code language: SQL (Structured Query Language) (sql) In this syntax: First, provide the table name to which you want to add a new column after the ALTER TABLE clause.
ALTER TABLE changes the structure of a table. For example, you can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or the table itself. You can also change characteristics such as the storage engine used for the table or the table comment.
