How to insert data in a row that already has data?

Databases
1

Could someone please show me how to insert data into a row that already has data. Something like this:

SETTING

`Column_4` int(3) DEFAULT NULL,

THIS IS ROW-3

col1 3 - col2 mike - col3 password - col4 is empty

I need to insert a single character (the number 1) into the empty field under column 4 for user “mike”. User name is primary I hope I worded this correctly. I’m using PHP-5.3.8 and MySQL-5.5.18 as localhost for learning.

Thanks in advance

2

I meant to say UPDATE and everything I tried using UPDATE did not work, that’s why I’m asking how-to. It’s easy if it has data but the field don’t have anything in it.

3

you want UPDATE, not INSERT

UPDATE updates a row (and lets you change any of the column values in that row), whereas INSERT inserts a completely brand new row

4 
UPDATE daTable
   SET column_4 = 1
 WHERE column_3 = 'mike'
5 
WHERE column_3 = 'mike'

That’s what got me. I was using where column-3 and such.

Thanks again r937

I get it now!