Hi,
I have met some strange situation... Could someone explain difference between LEFT and RIGHT JOIN? I thought it is just from whitch side we are looking in JOIN columns part... but it seems that is not the case....
I have three Tables with the same structure...
CREATE TABLE t1
(
id integer NOT NULL,
sometext text
CONSTRAINT t1_pk PRIMARY KEY (c1 )
)
WITH (
OIDS=FALSE
);
data in tables are
t1 t2 t3
1, t1row1 1, t2row1 1, t3row1
2, t1row2 2, t2row2
3, t1row3
I want to apply next query:
Get All text values from t1, relateded value from t2, in case you have found matched value in t2, show me related value from t3...
So expecting result is:
t1 t2 t3
t1row1 t2row1 t3row1
t1row2
t1row3
(row 2 from t2, is not in result because of there is no related row in t3
If we run query:
SELECT t1.sometext AS c1, t2.sometext AS c2, t3.sometext AS c3
FROM
t1
Result is unexpected to me:
t1 t2 t3
t1row1 t2row1 t3row1
The same result as we run:
SELECT t1.sometext AS c1, t2.sometext AS c2, t3.sometext AS c3
FROM
t1
but if we run
SELECT t1.sometext AS c1, t2.sometext AS c2, t3.sometext AS c3
FROM
t3
Result is expected!
Could anyone light the catch?
Thanks,
Misa
