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Setting similar value for a column in a MySQL table?
You can set value for a column of all records with the help of update command.
The syntax is as follows if you want set NULL value for all the records in a column −
update yourTableName set yourColumnName = NULL;
Or if you want to use empty string, the following is the syntax −
update yourTableName set yourColumnName = ’’;
To understand the above concept, let us create a table. The query to create a table.
mysql> create table StudentDemo −> ( −> Studentid int, −> StudentName varchar(100), −> Age int −> ); Query OK, 0 rows affected (0.64 sec)
The following is the table to insert records −
mysql> insert into StudentDemo values(1,'Johnson',23); Query OK, 1 row affected (0.18 sec) mysql> insert into StudentDemo values(2,'Carol',24); Query OK, 1 row affected (0.16 sec) mysql> insert into StudentDemo values(3,'David',20); Query OK, 1 row affected (0.18 sec) mysql> insert into StudentDemo values(4,'Bob',21); Query OK, 1 row affected (0.19 sec)
Display all records from the table with the help of select statement −
mysql> select *from StudentDemo;
The following is the output −
+-----------+-------------+------+ | Studentid | StudentName | Age | +-----------+-------------+------+ | 1 | Johnson | 23 | | 2 | Carol | 24 | | 3 | David | 20 | | 4 | Bob | 21 | +-----------+-------------+------+ 4 rows in set (0.00 sec)
Here is the query to set a column value to NULL for all records in a specific column. The query is as follows −
mysql> update StudentDemo set Age=NULL; Query OK, 4 rows affected (0.14 sec) Rows matched: 4 Changed: 4 Warnings: 0
Let us check now −
mysql> select *from StudentDemo;
The following is the output displaying that we have successfully updated the “Age” column to NULL −
+-----------+-------------+------+ | Studentid | StudentName | Age | +-----------+-------------+------+ | 1 | Johnson | NULL | | 2 | Carol | NULL | | 3 | David | NULL | | 4 | Bob | NULL | +-----------+-------------+------+ 4 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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