MySQL indexes a field in a table

Note: The `` in `table_name` and `column` is a key below Esc ~`, you can omit the ``, write the table name and field name directly

1. Add PRIMARY KEY (primary key index):

ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` )

2. Add UNIQUE (unique index):

ALTER TABLE `table_name` ADD UNIQUE ( `column` )

3. Add INDEX (normal index):

Writing 1: ALTER TABLE `table_name` ADD INDEX index_name ( `column` )

Writing 2: CREATE INDEX index_name ON `table_name`(`column1`,`column2`,`column3`)

4. Add FULLTEXT (full-text index):

ALTER TABLE `table_name` ADD FULLTEXT ( `column`)

5. Add a multi-column index:

Writing 1: ALTER TABLE `table_name` ADD INDEX index_name ( `column1`, `column2`, `column3` )

Writing 2: CREATE INDEX index_name ON `table_name`(`column1`,`column2`,`column3`)

SHOW INDEX FROM `table_name`;-- query table index

DROP INDEX index_name ON `table_name`;-- drop index