Question

I have been working with a postgresql database with a php project, and I am just trying to construct a query. This is the scenario.

Suppose I have several tables, FOO and BAR

Table FOO looks like this:

| foo_id | foo_name | foo_data  |
----------------------------------
|   1    | john     | son       |
|   2    | jane     | daughter  |
|   3    | sam      | son       |
|   4    | sally    | daughter  |

Table BAR looks like this

| bar_id | bar_foo_id | bar_fooParent_id | bar_content            |
----------------------------------
|   1    | 1          |       1          | yabba-dabba-doo        |
|   2    | 2          |       1          | scooby-scooby-doo      |
|   1    | 3          |       888        | don't have a cow, man  |
|   2    | 4          |       999        | d'oh!                  |

I can’t change the table schema, everything is as it is.

But – I can pass a value through PHP, let’s call it PARENT, that represents a value from bar_fooParent_id (so I can pass 1,2,3…657,888,999 etc).

And – foo_id in table FOO maps to bar_foo_id in table BAR.

I would like to build a SELECT Query that combines data from both tables FOO and BAR. Something like:

SELECT BAR.bar_content, (and other BAR.columns) , FOO.foo_name, FOO.foo_data 
FROM FOO,BAR WHERE bar_fooParent_id=".$PARENT." AND " ...?

where ? is a little confusing.

I need to grab rows for foo_name and foo_data from table FOO based upon the selected rows from table BAR. So if a value of 1 is passed to $PARENT, then bar_fooParent_id would be 1, I would get the first two rows from table BAR, and use their respective bar_foo_ids (with values 1 and 2) to grab the data from the rows of table FOO that have foo_ids of 1 and 2 (the first two rows in this case).

I have tried statements similar to those below (values are hard coded for simplicity)

SELECT * from BAR,FOO where BAR.bar_fooParent_id=1 AND (BAR.foo_id=1 OR BAR.foo_id=2) AND (FOO.foo_id=1 OR FOO.foo_id=3)

OR

select * from BAR where BAR.barr_fooParent_id=1 IN (SELECT foo_id,foo_name from kid WHERE foo_id=1 OR foo_id=3 ) 

without much success. Basically the data should return ideally as

foo_name  |  foo_data  | bar_content    | other BAR columns ... |
_________________________________________________________________
john      |  son       | yabba-dabba-do | etc.                  |
jane      |  daughter  | scooby-dooby-do| etc.                  |

(apologies for the formatting, not sure what is happening with this third table of results)

I’d appreciate it if someone can lend a hand in building this SELECT query for postgreSQL.

any ideas? and thanks.

Edward

Answer 1

Sounds like all you need is a simple join:

SELECT f.foo_name, f.foo_data, b.bar_content
FROM foo f
INNER JOIN bar b ON b.bar_foo_id = f.foo_id
WHERE b.bar_fooParent_id = 1