CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX
length)] [ASC|DESC], ...)
Use this statement to add an index to a table after it has been created. This is an alias of the clause of the ALTER TABLE statement that adds an index. You can add indexes only to MyISAM, InnoDB, and BDB types of tables. You can also create these tables with indexes, as shown in the CREATE TABLE statement later in this chapter.
To prevent duplicates, add the
UNIQUE flag between the
CREATE keyword and
VARCHAR data types of MyISAM tables can be indexed
Creating UNIQUE indexes
CREATE UNIQUE INDEX
INDEX keyword, the name of the index or key is given. This name can be
the same as one of the columns indexed, or a totally new name.
You can specify the type of index with the
USING keyword. For MyISAM and
BTREE is the default, but
RTREE is also available as of version 5.0 of MySQL.
TYPE keyword is an alias for
For wide columns, it may be advantageous to specify a maximum number of characters to use from a column for indexing. This can speed up indexing and reduce the size of index files on the filesystem.
Although there is an
ASC option for sorting
indexes in ascending order and a
DESC option for sorting in descending order, these are for a future release of MySQL. All indexes are currently sorted in ascending ...