How do I delete the value of a specific column from all the rows in a table?

I want to delete the value from a group of columns (say column 1,2,3 and not 4,5,6) from all the rows (say a,b,c,d,e,f,g) in my table (u_table). How would I do this?

I've been trying something with INSERT but I can't figure out how to do all the rows...

 

You need an UPDATE query. Most likely, since the value could be in any of 3 columns, you will need 3 update queries.

 

Actually, only 1 update query is sufficient.

UPDATE u_table
SET column_1='',
SET column_2='',
SET column_3=''

Code (markup):

 

^ +1 hit it on the head

 

If amount of columns is low then use phpmyadmin, if not then you really need some condition