Overview

DDL Statements that Can Be Executed on a MySQL Client

• TRUNCATE

  Example:

  TRUNCATE TABLE t1

  Deletes all data from table t1.

  TRUNCATE TABLE deletes all data from a table and has the DROP permission. In logic, TRUNCATE TABLE is similar to the DELETE statement for deleting all rows from a table.

• ALTER TABLE

  Example:

  ALTER TABLE t2 DROP COLUMN c, DROP COLUMN d;

  Deletes columns c and d fom table t2.

  ALTER can add or delete a column, create or drop an index, change the type of an existing column, rename columns or tables, or change the storage engine or comments of a table.

• DROP INDEX

  Example:

  DROP INDEX `PRIMARY` ON t;

  Deletes primary key from table t.

• CREATE INDEX

  Example:

  CREATE INDEX part_of_name ON customer (name(10));

  Creates an index using the first 10 characters in column name (assuming that there are non-binary character strings in column name).

  CREATE INDEX can add an index to an existing table.