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MySQL query that returns a specific string if column is null?
Let us first create a table −
mysql> create table DemoTable -> ( -> Name varchar(100) -> ); Query OK, 0 rows affected (0.85 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(NULL); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(NULL); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected (0.17 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable;
Output
+-------+ | Name | +-------+ | John | | NULL | | NULL | | David | +-------+ 4 rows in set (0.00 sec)
Here is the query that returns a specific string if column is null −
mysql> SELECT COALESCE(Name, 'Not Valid') from DemoTable;
Output
+-----------------------------+ | COALESCE(Name, 'Not Valid') | +-----------------------------+ | John | | Not Valid | | Not Valid | | David | +-----------------------------+ 4 rows in set (0.00 sec)
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