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How to check if data is NULL in MySQL?
You can use IF() to check if data is NULL. Let us first create a table −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(200), Age int ); Query OK, 0 rows affected (0.44 sec)
Insert records in the table using insert command −
mysql> insert into DemoTable(Name,Age) values('John',23);
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable(Name,Age) values('Sam',null);
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable(Name,Age) values('Mike',23);
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable(Name,Age) values('David',21);
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable(Name,Age) values('Carol',null);
Query OK, 1 row affected (0.13 sec)Display records from the table using select command −
mysql> select *from DemoTable;
This will produce the following output −
+----+-------+------+ | Id | Name | Age | +----+-------+------+ | 1 | John | 23 | | 2 | Sam | NULL | | 3 | Mike | 23 | | 4 | David | 21 | | 5 | Carol | NULL | +----+-------+------+ 5 rows in set (0.00 sec)
Here is the query to check if data is NULL or not. This adds a message wherever NULL in the record is visible −
mysql> select if(Age IS NULL,'Age is missing',Age) from DemoTable;
This will produce the following output −
+--------------------------------------+ | if(Age IS NULL,'Age is missing',Age) | +--------------------------------------+ | 23 | | Age is missing | | 23 | | 21 | | Age is missing | +--------------------------------------+ 5 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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