query index show index from table_name
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)
ALTER TABLE `table_name` ADD INDEX index_name (
` column`
) `, `column2`, `column3` )