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The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table.
This is a MySQL extension to standard SQL, which permits only one of each clause per ALTER TABLE statement. For example, to drop multiple columns in a single statement, do this: ALTER TABLE t2 DROP COLUMN c, DROP COLUMN d; If a storage engine does not support an attempted ALTER TABLE operation, a warning may result.
In this article, we described how to use the ALTER TABLE statement modify a table, including: adding columns, deleting columns, modifying columns, renaming columns, renaming tables, setting primary keys, etc.
You will learn how to use the MySQL ALTER TABLE statement to add a column, alter a column, rename a column, drop a column and rename a table.
To rename the table from t1 to t2: ALTER TABLE t1 RENAME t2; To change column a from INTEGER to TINYINT NOT NULL (leaving the name the same), and to change column b from CHAR(10) to CHAR(20) as well as renaming it from b to c: ALTER TABLE t2 MODIFY a TINYINT NOT NULL, CHANGE b c CHAR(20);
To change the name of an existing table, you use the RENAME table keyword along with the ALTER TABLE statement. Syntax: ALTER TABLE table_name RENAME TO new_table_name;
This MySQL tutorial explains how to use the MySQL ALTER TABLE statement to add a column, modify a column, drop a column, rename a column or rename a table (with syntax and examples).
