Don't update column if update value is null

Question

I have a query like this (in a function):

UPDATE some_table SET   column_1 = param_1,   column_2 = param_2,   column_3 = param_3,   column_4 = param_4,   column_5 = param_5 WHERE id = some_id; 

Where param_x is a parameter of my function. Is there a way to NOT update those columns, for which the param is NULL? For example - if param_4 and param_5 are NULL, then update only the first three columns and leave old values for column_4 and column_5.

The way I am doing it now is:

SELECT * INTO temp_row FROM some_table WHERE id = some_id;  UPDATE some_table SET   column_1 = COALESCE(param_1, temp_row.column_1),   column_2 = COALESCE(param_2, temp_row.column_2),   column_3 = COALESCE(param_3, temp_row.column_3),   column_4 = COALESCE(param_4, temp_row.column_4),   column_5 = COALESCE(param_5, temp_row.column_5) WHERE id = some_id; 

Is there a better way?

Answer 1

Drop the SELECT statement, there is no need for, just use the current value:

UPDATE some_table SET   column_1 = COALESCE(param_1, column_1),   column_2 = COALESCE(param_2, column_2),   column_3 = COALESCE(param_3, column_3),   column_4 = COALESCE(param_4, column_4),   column_5 = COALESCE(param_5, column_5) WHERE id = some_id;