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How to check whether column value is NULL or having DEFAULT value in MySQL?
You can use the concept of IFNULL() for this. Let us first create a table −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(100) DEFAULT 'Larry', Age int DEFAULT NULL ); Query OK, 0 rows affected (0.73 sec)
Insert records in the table using insert command −
mysql> insert into DemoTable(Name,Age) values('John',23);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values();
Query OK, 1 row affected (0.34 sec)
mysql> insert into DemoTable(Name) values('David');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable(Age) values(24);
Query OK, 1 row affected (0.13 sec)Following is the query to display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+-------+------+ | Id | Name | Age | +----+-------+------+ | 1 | John | 23 | | 2 | Larry | NULL | | 3 | David | NULL | | 4 | Larry | 24 | +----+-------+------+ 4 rows in set (0.00 sec)
Following is the query to check whether column value is NULL or having DEFAULT value in MySQL.
mysql> select *from DemoTable WHERE IFNULL(Name, DEFAULT(Name)) <> DEFAULT(Name);
This will produce the following output −
+----+-------+------+ | Id | Name | Age | +----+-------+------+ | 1 | John | 23 | | 3 | David | NULL | +----+-------+------+ 2 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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