Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Treat a MySQL column field as NULL if it is blank?
Let us first create a table −
mysql> create table DemoTable1362 -> ( -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ClientName varchar(40) -> ); Query OK, 0 rows affected (0.67 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1362(ClientName) values('Chris');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable1362(ClientName) values(' ');
Query OK, 1 row affected (0.08 sec)
mysql> insert into DemoTable1362(ClientName) values('Bob');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable1362(ClientName) values(' ');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1362(ClientName) values('David');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable1362(ClientName) values(NULL);
Query OK, 1 row affected (0.07 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1362;
This will produce the following output −
+----------+------------+ | ClientId | ClientName | +----------+------------+ | 1 | Chris | | 2 | | | 3 | Bob | | 4 | | | 5 | David | | 6 | NULL | +----------+------------+ 6 rows in set (0.00 sec)
Following is the query to treat a column field as null if it is blank −
mysql> update DemoTable1362 -> set ClientName=NULL -> where ClientName='' or length(ClientName)=0; Query OK, 2 rows affected (0.21 sec) Rows matched: 2 Changed: 2 Warnings: 0
Let us check the table records once again −
mysql> select * from DemoTable1362;
This will produce the following output −
+----------+------------+ | ClientId | ClientName | +----------+------------+ | 1 | Chris | | 2 | NULL | | 3 | Bob | | 4 | NULL | | 5 | David | | 6 | NULL | +----------+------------+ 6 rows in set (0.00 sec)
Updated on: 08-Nov-2019
133 Views
Advertisements