SQL Alter Table Indexes

Creating Indexes with the ALTER TABLE statement.

In some RDBMS you can create indexes with the ALTER TABLE statement.
Syntax:
MySQL:
ALTER TABLE table_name
  ADD [UNIQUE] INDEX constraint_name (column_name, ....),
  ADD [UNIQUE] INDEX constraint_name (column_name, ....), .....;
Add Index example:
ALTER TABLE BOOKSTORE
  ADD INDEX SHORT_IND (SHORT_DESC),
  ADD INDEX ISNB_AUTHOR_IND (ISBN_NO, AUTHOR);
The index, ISNB_AUTHOR_IND, is defined as a composite index for ISBN_NO and AUTHOR columns, while SHORT_IND is an index for a single column, SHORT_DESC.
Add Unique Index example:
ALTER TABLE BOOKSTORE
  ADD UNIQUE INDEX SHORTDESC_IND (SHORT_DESC, PUBLISHER),
  ADD UNIQUE INDEX AUTHOR_IND (AUTHOR);
The index, SHORT_DESC_IND, is defined as a composite unique index for SHORT_DESC and PUBLISHER columns, while the AUTHOR_IND is a UNIQUE INDEX for a single column, AUTHOR.
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