What are the methods of creating indexes in mysql

Editor to share with you the methods of mysql to create an index, I hope you will learn a lot after reading this article, let's discuss it together!

You can create an index when you execute a CREATE TABLE statement, or you can add an index to a table using CREATE INDEX or ALTER TABLE alone.

1.ALTER TABLE

ALTER TABLE is used to create normal, UNIQUE, or PRIMARY KEY indexes.

ALTER TABLE table_name ADD INDEX index_name (column_list) ALTER TABLE table_name ADD UNIQUE (column_list) ALTER TABLE table_name ADD PRIMARY KEY (column_list)

Where table_name is the name of the table to be indexed, column_list indicates which columns are indexed, and multiple columns are separated by commas. The index name index_name is optional, and by default, MySQL assigns a name based on the first index column. In addition, ALTER TABLE allows multiple tables to be changed in a single statement, so multiple indexes can be created at the same time.

2.CREATE INDEX

CREATE INDEX can add a normal index or an UNIQUE index to a table.

CREATE INDEX index_name ON table_name (column_list) CREATE UNIQUE INDEX index_name ON table_name (column_list)

Table_name, index_name, and column_list have the same meaning as in the ALTER TABLE statement, and the index name is not optional. In addition, PRIMARY KEY indexes cannot be created with CREATE INDEX statements.

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