I have 4 different tables that I want to join. The tables are structured with columns as follows:
TableA - aID | nameA | dID
TableB - bID | nameB | cID | aID
TableC - cID | nameC | date
TableD - dID | nameD
Starting with Table A, I understand how to JOIN tables a and c using b, since b has the
Primary Keys for those tables. I want to be able to join table TableD on TableA as well.
Below is my SQL statement that first joins tables A and B, then joins that to C:
SELECT TableA.*, TableB.*, TableC.* FROM (TableB INNER JOIN TableA
ON TableB.aID= TableA.aID)
INNER JOIN TableC ON(TableB.cID= Tablec.cID)
WHERE (DATE(TableC.date)=date(now()))
When I attempt to add another join, to include D, I get an error that 'TableD' is unknown:
SELECT TableA.*, TableB.*, TableC.*, TableD.* FROM (TableB INNER JOIN TableA
ON TableB.aID= TableA.aID)
INNER JOIN TableC ON(TableB.cID= Tablec.cID)
INNER JOIN TableA ta ON(ta.dID= TableD.dID)
WHERE (DATE(TableC.date)=date(now()))
Answers
You want something more like this:
SELECT TableA.*, TableB.*, TableC.*, TableD.*
FROM TableA
JOIN TableB
ON TableB.aID = TableA.aID
JOIN TableC
ON TableC.cID = TableB.cID
JOIN TableD
ON TableD.dID = TableA.dID
WHERE DATE(TableC.date)=date(now())
In your example, you are not actually including
TableD
. All you have to do is perform
another join just like you have done before.
A note: you will notice that I removed many of your parentheses, as they really are not
necessary in most of the cases you had them, and only add confusion when trying to read
the code. Proper nesting is the best way to make your code readable and separated out.
You have not joined TABLED merely selected the FIELD TABLED from one of the tables.
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