How do I delete blank rows in Mysql?

Question

I do have a table with more than 100000 data elements, but there are almost 350 blank rows within. How do I delete this blank rows using phpmyadmin? Manually deleting is a tedious task.

Answer 1

The general answer is:

DELETE FROM table_name WHERE some_column = '';

or

DELETE FROM table_name WHERE some_column IS NULL;

See: http://dev.mysql.com/doc/refman/5.0/en/delete.html

More info when you post your tables!~

Also, be sure to do:

SELECT * FROM table_name WHERE some_column = '';

before you delete, so you can see which rows you are deleting! I think in phpMyAdmin you can even just do the select and then "select all" and delete, but I'm not sure. This would be pretty fast, and very safe.

Answer 2

I am doing the mysql operation in command prompt in windows. And the basic queries:

delete * from table_name where column=''

and

delete * from table_name where column='NULL'

doesn't work. I don't know whether it works in phpmyadmin sqlcommand builder. Anyway:

delete * from table_name where column is NULL 

works fine.

Answer 3

I have a PHP script that automatically removes empty rows based on column data types.

That allows me to define "emptiness" differently for different column types.

e.g.

table
first_name (varchar) | last_name (varchar) | some_qty ( int ) | other_qty (decimal)

DELETE FROM `table` WHERE
(`first_name` IS NULL OR `first_name` = '')
AND
(`last_name` IS NULL OR `last_name` = '')
AND
(`some_qty` IS NULL OR `some_qty` = 0)
AND
(`other_qty` IS NULL OR `other_qty` = 0)

Since "0" values are meaningless in my system, I count them as empty. But I found out that if you do (first_name = 0) then you will always get true, because strings always == 0 in MySQL. So I tailor the definition of "empty" to the data type.