mysql - possible to join on more than one field?
I'm trying to write a join statement, but am finding that the query I'm running开发者_开发百科 outputs the same information for each title found. It seems like I need to join tables on multiple fields, and I'm not sure that's possible? It's a little hard to explain, but the code below shows what I'm trying to accomplish and what's actually happening... Hopefully, someone will be able to point me in the right direction?
+----------------------------------------------------+
TABLE: NODE N
+----------------------------------------------------+
nid | vid | type | language | title | uid
22196 | 22196 | einfo | en | Contact 15 | 15
22040 | 22040 | fmp | en | John Doe | 15
22043 | 22043 | fmp | en | Jane Doe | 15
+----------------------------------------------------+
TABLE: CONTENT_FIELD_PN P
+----------------------------------------------------+
vid | nid | delta | field_name_nid
22196 | 22196 | 0 | 22040
22196 | 22196 | 1 | 22043
+----------------------------------------------------+
TABLE: CONTENT_FIELD_PP PP
+----------------------------------------------------+
vid | nid | delta | field_homephone_value
22196 | 22196 | 0 | 6505551212
22196 | 22196 | 1 | 6505551444
I'm trying to write a join statement that will produce:
+----------------------------------------------------+
TRYING TO OUTPUT
+----------------------------------------------------+
title | field_homephone_value | delta
John Doe | 6505551212 | 0
Jane Doe | 6505551444 | 1
+----------------------------------------------------+
WHAT IS CURRENTLY BEING OUTPUT
+----------------------------------------------------+
title | field_homephone_value | delta
John Doe | 6505551212 | 0
Jane Doe | 6505551212 | 1
+----------------------------------------------------+
THE QUERY AS IT'S CURRENTLY WRITTEN
+----------------------------------------------------+
SELECT p.field_name_nid, n2.title, p.delta, pp.field_homephone_value
FROM node n
LEFT JOIN content_field_pn p ON n.nid = p.nid
LEFT JOIN node n2 ON p.field_name_nid = n2.nid
LEFT JOIN content_field_pp pp ON p.nid = pp.nid
WHERE n.nid = 22196
GROUP BY p.delta
You could use and
in the on
clause:
LEFT JOIN content_field_pp pp ON p.nid = pp.nid AND p.vid = pp.vid
^^^^^^^^^^^^^^^^^^
You may join on multiple fields...
SELECT `blah` FROM `a` LEFT JOIN `b` ON `b`.`id` = `a`.`id` AND `b`.`field2` = `a`.`field2`
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