I have 3 tables listing below:
Table_A:
order_number | header_id
123 | 80001
Table_B
header_id | line_id | quantity
80001 | 10001 | 1
80001 | 10002 | 3
80001 | 10003 | 5
Table_C
header_id | line_id | hold_price_id | released_flag
80001 | 10001 | 2001 | Y
80001 | 10002 | 2002 | Y
80001 | 10003 | 2003 | N
I wrote a query as shown below:
SELECT A.order_number, A.header_id, B.line_id, B.quantity, C.hold_price_id, C.released_flag
FROM Table_A a,
Table_B b,
Table_C c
WHERE a.header_id = b.header_id
AND c.line_id = b.line_id
AND a.order_number = '123';
My desire output is as shown below:
order_number | header_id | line_id | quantity | hold_price_id | released_flag
123 | 80001 | 10001 | 1 | 2001 | Y
123 | 80001 | 10002 | 3 | 2002 | Y
123 | 80001 | 10003 | 5 | 2003 | N
However the query show me the below result:
order_number | header_id | line_id | quantity | hold_price_id | released_flag
123 | 80001 | 10001 | 1 | 2001 | Y
123 | 80001 | 10001 | 3 | 2002 | Y
123 | 80001 | 10001 | 5 | 2003 | N
123 | 80001 | 10002 | 1 | 2001 | Y
123 | 80001 | 10002 | 3 | 2002 | Y
123 | 80001 | 10002 | 5 | 2003 | N
123 | 80001 | 10003 | 1 | 2001 | Y
123 | 80001 | 10003 | 3 | 2002 | Y
123 | 80001 | 10003 | 5 | 2003 | N
Is it something wrong on my query? Please advice.
Thank you!
You need to learn to use proper explicit join
syntax. A simple rule: never use commas in the from
clause. Always use explicit join
s:
SELECT A.order_number, A.header_id, B.line_id, B.quantity,
C.hold_price_id, C.released_flag
FROM Table_A a JOIN
Table_B b
ON a.header_id = b.header_id JOIN
Table_C c
ON c.header_id = b.header_id AND c.line_id = b.line_id
WHERE a.order_number = '123';
You haven't joined all of the common keys, so you are getting Cartesian results. You needs to join a to c with header id, like so
SELECT A.order_number, A.header_id, B.line_id, B.quantity, C.hold_price_id, C.released_flag
FROM Table_A a,
Table_B b,
Table_C c
WHERE a.header_id = b.header_id
AND c.line_id = b.line_id
AND a.header_id = c.header_id
AND a.order_number = '123';
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