PHP MYSQL SELECT even if some are empty

Question

I am not too familiar with SQL, but I need to select from 3 tables.

I can go:

SELECT * FROM tbl1, tbl2, tbl3 WHERE ID=3

but there is a chance that tbl3 is does not have any rows with ID 3, and chances are that tbl1 has a few.

tbl2 should have only one row.

I would still like to get the rows in the other tables.

How can I accomplish this ?

Thanks up ahead!

what's the table structure? is there any relationship between the tables? — user557846
– user557846, Commented Sep 6, 2011 at 23:12

Doug Kress · Accepted Answer · 2011-09-06 23:14:01Z

1

How do the three tables relate? The condition 'WHERE ID=3' is a little ambiguous - does ID exist in all three tables, and you want all records from each table where ID = 3?

The bottom line is you need to use a LEFT JOIN to join the tables together, but it's hard to give an example without knowing how the tables relate.

Making some assumptions:

SELECT *
FROM tbl1
LEFT JOIN tbl2 ON tbl2.tbl1_id = tbl1.id
LEFT JOIN tbl3 ON tbl3.tbl1_id = tbl1.id
WHERE tbl1.id = 3;

answered Sep 6, 2011 at 23:14

Doug Kress

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1 Comment

Ted Over a year ago

well, all three tables have a row named b_ID, table1 might 0 or more instances of b_ID=3 for example, whereas table3 might not have any at all. From what I read here: w3schools.com/sql/sql_join_left.asp this is the answer, thanks

carlgcode · Accepted Answer · 2011-09-06 23:12:47Z

0

Do seperate queries of each table, then do a row count of those queries, then with the results
you can do if elseif else statements to do wat you want to do.

answered Sep 6, 2011 at 23:12

carlgcode

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