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How to implement MySQL ORDER BY x where (x=col3 if col3!=null, else x=col2)?
For this, you can use ORDER BY IFNULL(). Let us first create a table −
mysql> create table DemoTable -> ( -> Name varchar(20), -> CountryName varchar(20) -> ); Query OK, 0 rows affected (0.61 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values('Chris',NULL);
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values('David','AUS');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values(NULL,'UK');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable values(NULL,'AUS');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values(NULL,NULL);
Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+-------+-------------+ | Name | CountryName | +-------+-------------+ | Chris | NULL | | David | AUS | | NULL | UK | | NULL | AUS | | NULL | NULL | +-------+-------------+ 5 rows in set (0.00 sec)
Here is the query to implement MySQL ORDER BY x where (x=col3 if col3!=null, else x=col2) −
mysql> select *from DemoTable -> order by ifnull(Name,CountryName);
This will produce the following output −
+-------+-------------+ | Name | CountryName | +-------+-------------+ | NULL | NULL | | NULL | AUS | | Chris | NULL | | David | AUS | | NULL | UK | +-------+-------------+ 5 rows in set (0.00 sec)
Updated on: 17-Dec-2019
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