SELECT * FROM mytable WHERE column3 IS NOT NULL;
eller hvad mener du med sådan noget?
SELECT * FROM mytable WHERE column3 = 'yes' AND column1 IS NOT NULL;
SELECT * FROM mytable WHERE column3 IS NOT NULL;
eller hvad mener du med sådan noget?
SELECT * FROM mytable WHERE column3 = 'yes' AND column1 IS NOT NULL;