SQL: UPDATE table SET column_x = a WHERE column_y = ' '; if I want to only update rows with omitted fields in a different column?

Question

SQL: UPDATE table SET column_x = a WHERE column_y = ' ';

or

SQL: UPDATE table SET column_x = a WHERE column_y = 'null';

or

SQL: UPDATE table SET column_x = a WHERE column_y = ('null');

Answer 1

UPDATE table SET column_x = a WHERE column_y IS NULL;



'' refers to an empty string which is different to a null string, ' ' is a string containing a space and 'null' is not a null string but a string containing the word "null".

Answer 2

If your goal is to only update rows where another column is empty, then I would do this:



UPDATE table SET column_x = a WHERE column_y = '' OR column_y IS NULL;

Answer 3

agree with Jeff's answer over Fiona's. Her solution does not account for zero length string