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    <p>If I understand correctly, then there should be a <strong>much simpler</strong> solution.</p> <h3>Test setup</h3> <p>According to your description - you could have done that for us:</p> <pre><code>CREATE TABLE table1 ( entry_id int4 PRIMARY KEY , entry_date date ); CREATE TABLE table2 ( entry_id int4 REFERENCES table1 (entry_id) , entry_subject text , PRIMARY KEY (entry_id, entry_subject) ); INSERT INTO table1 VALUES (1, '2011-09-01'), (2, '2011-09-02'),(3, '2011-09-03'); INSERT INTO table2 VALUES (1, 'foo1'), (2, 'foo2'), (2, 'bar2') , (3, 'foo3'), (3, 'baz3'), (3, 'bar3'); </code></pre> <h3>Answer</h3> <p><code>string_agg()</code> requires Postgres 9.0+</p> <pre><code>SELECT t1.entry_id, t1.entry_date , string_agg(t2.entry_subject, ', ') AS entry_subjects FROM table1 t1 JOIN table2 t2 USING (entry_id) GROUP BY 1,2 ORDER BY 1; entry_id | entry_date | entry_subjects ----------+------------+------------------ 1 | 2011-09-01 | foo1 2 | 2011-09-02 | bar2, foo2 3 | 2011-09-03 | baz3, bar3, foo3 </code></pre> <p>Or, if you want the entry_subjects <strong>sorted</strong>:</p> <pre><code>SELECT DISTINCT ON (1) t1.entry_id , t1.entry_date , string_agg(t2.entry_subject, ', ') OVER ( PARTITION BY t1.entry_id ORDER BY t2.entry_subject RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS entry_subjects FROM table1 t1 JOIN table2 t2 USING (entry_id) ORDER BY 1; entry_id | entry_date | entry_subjects ----------+------------+------------------ 1 | 2011-09-01 | foo1 2 | 2011-09-02 | bar2, foo2 3 | 2011-09-03 | bar3, baz3, foo3 </code></pre> <p>You could do the same with a subselect on <code>table2</code> to first <code>ORDER BY entry_subject</code>.</p>
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    1. COThe string_agg function was only introduced in postgres 9.0, and I have an earlier version. However, this gave me the idea to use a combination of array_to_string and array_agg to do the same thing that string_agg does. Thanks a bunch for the help!
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    2. COYeah, string_agg() is just a (very convenient) shortcut for array_to_string(array_agg(..))
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