How to Create the Index in MySQL?
This crucial MySQL tutorial will explain MySQL’s index method, how to create, rename or drop them with help of different syntax es. This article will help MySQL career pursuers with multiple MySQL interview questions, so make sure to continue until the end to acknowledge important career supporting technical details.
So, What is MySQL’s Index?
In MySQL, the index is a comprehensive data structure that highly improves operation speed in a table. We can create indexes using one or multiple columns, offering the base for an efficient ordering of access to records and quick random look ups. Literally, indexes are a type of tables that keep index field or primary key and a pointer to record into the actual table. Indexes can’t be seen by users. They are simply used to fasten queries and will be used to locate records fast by the Database Search Engine.
How to Create an Index in MySQL?
This could be an important MySQL interview question, so readers are advised to go through it carefully. We can create indexes in two ways, either by creating an index while first creating a table using the CREATE TABLE statement or using the CREATE INDEX statement afterthe creation of the table.
For the CREATE INDEX statement use for index creation, use this syntax set.
CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX index_name
[ USING BTREE | HASH ]
ON table_name
(index_col1 [(length)] [ASC | DESC],
index_col2 [(length)] [ASC | DESC],
...
index_col_n [(length)] [ASC | DESC]);
Now, let’s define the properties in the above CREATE INDEXsyntax.
Unique: This is an optional modifier which will indicate the combination of values present in the indexed columns must stay unique.
SPATIAL: This is also an optional modifier which indexes the complete column and doesn’t allow NULL values in the indexed columns. This option is supported by both MyISAM and InnoDB (version 5.7 above).
FULLTEXT: An optional modifier that indexes the entire column without allowing any prefixing. This one is also supported both by MyISAM and InnoDB.
How to Drop an Index in MySQL?
To drop an index in MySQL, we have to use the DROP INDEX statement. The syntax will be as follows.
Syntax:
DROP INDEX index_name
ON table_name;
How to Rename an Index?
Users can rename an index using the ALTER TABLE statement, which is only available for MySQL version 5.6 and later.
Syntax:
ALTER TABLE table_name
RENAME INDEX index_name TO new_index_name;
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