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Display first non-null values with coalesce() in MySQL?
The coalesce() can be used to print first NOT NULL column value. Let us first create a table −
mysql> create table DemoTable1927 ( StudentName varchar(20), StudentSubject varchar(20) ); Query OK, 0 rows affected (0.00 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1927 values('Chris','MySQL');
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1927 values('David',NULL);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1927 values(NULL,'MongoDB');
Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1927;
This will produce the following output −
+-------------+----------------+ | StudentName | StudentSubject | +-------------+----------------+ | Chris | MySQL | | David | NULL | | NULL | MongoDB | +-------------+----------------+ 3 rows in set (0.00 sec)
Here is the query to implement coalesce() in MySQL −
mysql> select coalesce(StudentName,StudentSubject) as Result from DemoTable1927;
This will produce the following output −
+---------+ | Result | +---------+ | Chris | | David | | MongoDB | +---------+ 3 rows in set (0.00 sec)
Updated on: 30-Dec-2019
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