-------- Original Message --------
Subject: Select...
From: Miguel Guirao <miguel.guirao@xxxxxxxxxxxxxxx>
To: php-db@xxxxxxxxxxxxx
Date: 15.1.2008 4:44
Hello List,
I'm having kind of trouble to get done this: Select data from a table,
except those data already in a second table. Actually, if there is a rowid
in table2, I wont get it from table1, rowid is the key that relates both
tables.
I just can't express this with a SQL statement!! idequipomed is the key that
relates both tables!!
So, if idequipomed is already in Table2, I shouldn't get it from Table1.
Any suggestions?
Many ways to do this. Choose the solution that gives you the best
performance.
Solution 1:
SELECT t2.idequipomed
FROM table2 t2
WHERE NOT EXISTS (
SELECT 1 FROM table1 WHERE table1.idequipomed = t2.idequipomed
)
Solution 2:
SELECT idequipomed
FROM table2
WHERE idequipomed NOT IN (SELECT idequipomed FROM table1)
Solution 3:
SELECT table2.idequipomed
FROM table2
LEFT JOIN table1 ON table1.idequipomed = table2.idequipomed
WHERE table1.idequipomed IS NULL
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