SQL query for displaying related values on same column as separate columns

Question

I have a table structure similar to this in an SQLITE database, with the LANID being a FK to another table:

ID   LANID    TEXT
-------------------------
1     101     Issue1
1     102     Comment1 for Issue1 
2     101     Issue2 
2     102     Comment1 for Issue2
3     101     Issue3
3     102     Comment1 for Issue3
1     102     Comment2 for Issue1
...

I am trying to fetch values from the TEXT field that share the same ID, using queries like this:

SELECT t.TEXT as issue, s.TEXT as comment
FROM MyTable as t, MyTable as s 
WHERE t.LANID = '101' and s.LANID = '102' AND t.ID = s.ID 
      AND t.TEXT like "%some text in Issue1%"

and it almost works, but with one problem: it can't "duplicate" values when needed. In other words, I can't display the second comment for the same issue like this:

issue               comment
---------------------------------
Issue1        Comment1 for Issue1
Issue1        Comment2 for Issue1 
...

Thanks in advance for any hints.

Answer 1

I would use an explicit self join , instead of the implicit join used in your original query:

SELECT
  mt1.Text AS Issues,
  mt2.Text AS Comment
FROM MyTable mt1
JOIN Mytable mt2
  ON mt1.ID = mt2.ID
  AND mt1.LANID = 101
  AND mt2.LANID = 102

See it in action with Sql Fiddle .

Answer 2

I think the problem is really about how you've set up your database. Comments should be in a seperate table referencing the issues with a foreign key. Without a sound database design, you'll always be struggling with kind of thing.

Answer 3

Your query does show the second comment. See this example at SQL Fiddle .

For a better way to write a join , see Michael Fredrickson's answer .