How to Create, List or Drop Indexes on MySQL Table

Indexes are very useful to improve search queries on database tables. For example you are searching for particular record in a database table having millions of records. You will find that search queries taking very less time on tables having indexes enables.

CREATE INDEX:-

This will creates index on mysql table. This will allow duplicate values also.

CREATE INDEX index_name ON table_name (COLUMN_NAME1, COLUMN_NAME2, ...) 

CREATE UNIQUE INDEX:-

This will creates index on mysql table. With uses of UNIQUE keyword this will not allow duplicate values.

CREATE UNIQUE INDEX index_name ON table_name (COLUMN_NAME1, COLUMN_NAME2, ...) 

1. CREATE INDEX Examples:-

For this example I have a table named Users with thousands of records in mysql database. The table structure is as following in screenshot.

Now use following command to create index named Users_Idx1 on table Users based on column username.

mysql> CREATE INDEX Users_Idx1 ON Users (username); 

Use UNIQUE keyword with the query to create index with unique records.

mysql> CREATE UNIQUE INDEX Users_Idx1 ON Users (username); 

2. SHOW INDEX Examples:-

Use following sql command to list all indexes for a mysql table. The below query will delete Users_Idx1 index from Users table in current database.

mysql> SHOW INDEX FROM Users; 

3. DELETE INDEX Examples:-

Use following sql command to delete index on mysql table.

mysql>  ALTER TABLE Users DROP INDEX Users_Idx1; 

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