How do I add indices to MySQL tables?

Question

I\'ve got a very large MySQL table with about 150,000 rows of data. Currently, when I try and run

SELECT * FROM table WHERE id = \'1\';

the

Answer 1

Indexes of two types can be added: when you define a primary key, MySQL will take it as index by default.

Explanation

Primary key as index

Consider you have a tbl_student table and you want student_id as primary key:

ALTER TABLE `tbl_student` ADD PRIMARY KEY (`student_id`)

Above statement adds a primary key, which means that indexed values must be unique and cannot be NULL.

Specify index name

ALTER TABLE `tbl_student` ADD INDEX student_index (`student_id`)

Above statement will create an ordinary index with student_index name.

Create unique index

ALTER TABLE `tbl_student` ADD UNIQUE student_unique_index (`student_id`)

Here, student_unique_index is the index name assigned to student_id and creates an index for which values must be unique (here null can be accepted).

Fulltext option

ALTER TABLE `tbl_student` ADD FULLTEXT student_fulltext_index (`student_id`)

Above statement will create the Fulltext index name with student_fulltext_index, for which you need MyISAM Mysql Engine.

How to remove indexes ?

DROP INDEX `student_index` ON `tbl_student`

How to check available indexes?

SHOW INDEX FROM `tbl_student`