Find and Replace Special Characters in MySQL

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)