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Return records that do not have a value in a certain field with two SELECT statement in a single MySQL query
For this, you can use WHERE clause along with subquery. Let us first create a table −
mysql> create table DemoTable1840
(
UserName varchar(20),
UserType ENUM('GUEST','ADMIN')
);
Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −
mysql> insert into DemoTable1840 values('Chris','Admin');
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1840 values('David','Guest');
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1840 values('Chris','Guest');
Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1840;
This will produce the following output −
+----------+----------+ | UserName | UserType | +----------+----------+ | Chris | ADMIN | | David | GUEST | | Chris | GUEST | +----------+----------+ 3 rows in set (0.00 sec)
Here is the query to records that do not have a value in a certain field:
mysql> select UserName from DemoTable1840 where UserName NOT IN(select UserName from DemoTable1840 where UserType='Admin');
This will produce the following output −
+----------+ | UserName | +----------+ | David | +----------+ 1 row in set (0.00 sec)
Updated on: 26-Dec-2019
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