MySQL: How can I find a value with special character and replace with NULL?

For this, use SET yourColumnName = NULL as in the below syntax −

update yourTableName set yourColumnName=NULL where yourColumnName=yourValue;

Let us first create a table −

mysql> create table DemoTable1914    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Code varchar(20)    )AUTO_INCREMENT=1001; Query OK, 0 rows affected (0.00 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1914(Code) values('John101'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1914(Code) values('234David'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1914(Code) values('100_Mike'); Query OK, 1 row affected (0.00 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1914;

This will produce the following output −

+------+----------+ | Id   | Code     | +------+----------+ | 1001 | John101  | | 1002 | 234David | | 1003 | 100_Mike | +------+----------+ 3 rows in set (0.00 sec)

Here is the query to find a value and replace with NULL −

mysql> update DemoTable1914    set Code=NULL    where Code='100_Mike'; Query OK, 1 row affected (0.00 sec) Rows matched: 1  Changed: 1 Warnings: 0

Let us check the table records once again −

mysql> select * from DemoTable1914;

This will produce the following output −

+------+----------+ | Id   | Code     | +------+----------+ | 1001 | John101  | | 1002 | 234David | | 1003 | NULL     | +------+----------+ 3 rows in set (0.00 sec)