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The MySQL EXPLAIN keyword executes the query or just explains the query?
The EXPLAIN keyword tells how MySQL executes the query. Let us first create a table −
mysql> create table DemoTable1375 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20), -> INDEX FIRST_INDEX(FirstName) -> ); Query OK, 0 rows affected (0.73 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1375(FirstName) values('Chris');
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable1375(FirstName) values('Bob');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable1375(FirstName) values('Sam');
Query OK, 1 row affected (1.06 sec)
mysql> insert into DemoTable1375(FirstName) values('David');
Query OK, 1 row affected (0.09 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1375;
This will produce the following output −
+----+-----------+ | Id | FirstName | +----+-----------+ | 2 | Bob | | 1 | Chris | | 4 | David | | 3 | Sam | +----+-----------+ 4 rows in set (0.00 sec)
Here is the query using MySQL EXPLAIN −
mysql> explain select * from DemoTable1375;
This will produce the following output −
+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+---------------+------------+-------+---------------+-------------+---------+------+------+----------+-------------+ | 1 | SIMPLE | DemoTable1375 | NULL | index | NULL | FIRST_INDEX | 63 | NULL | 4 | 100.00 | Using index | +----+-------------+---------------+------------+-------+---------------+-------------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.03 sec)
Updated on: 11-Nov-2019
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