How to correctly enclose subquery in MySQL?

MySQLMySQLi Database

You need to close the subquery in a parenthesis. The syntax is as follows −

select if((select count(*) from yourTableName ),'Yes','No') as anyAliasName;

To understand the above syntax, let us create a table. The query to create a table is as follows −

mysql> create table SelectIfDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Name varchar(10)
   -> );
Query OK, 0 rows affected (1.03 sec)

Insert some records in the table using insert command. The query is as follows −

mysql> insert into SelectIfDemo(Name) values('John');
Query OK, 1 row affected (0.21 sec)
mysql> insert into SelectIfDemo(Name) values('Carol');
Query OK, 1 row affected (0.17 sec)
mysql> insert into SelectIfDemo(Name) values('Larry');
Query OK, 1 row affected (0.12 sec)
mysql> insert into SelectIfDemo(Name) values('Bob');
Query OK, 1 row affected (0.22 sec)
mysql> insert into SelectIfDemo(Name) values('Sam');
Query OK, 1 row affected (0.15 sec)

Now you can display all records from the table using a select statement. The query is as follows −

mysql> select *from SelectIfDemo;

The following is the output −

+----+-------+
| Id | Name  |
+----+-------+
|  1 | John  |
|  2 | Carol |
|  3 | Larry |
|  4 | Bob   |
|  5 | Sam   |
+----+-------+
5 rows in set (0.00 sec)

Here is the correct way to use a subquery inside enclose parenthesis. The query is as follows −

mysql> select if((select count(*) from SelectIfDemo),'Yes','No') as Result;

The following is the output −

+--------+
| Result |
+--------+
| Yes    |
+--------+
1 row in set (0.00 sec)
raja
Published on 27-Feb-2019 08:16:54
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