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I have the following tables:

 

board_pcbs

 

id  |  pcb_type |  sap_pn

----------------------

1  | Type1 | 29-23032-02

----------------------

2  | Type2 | 29-30230-01

----------------------

 

board_tracking

 

id | type | serial | date_entered

-------------------------------------

1  | Type1    | 1231 | 2007-01-01 00:00:01

-------------------------------------

2  | Type1    | 2343 | 2007-01-01 00:00:31

-------------------------------------

3  | Type2    | 2399 | 2007-01-01 00:01:02

-------------------------------------

 

Now I understand I could of pointed the board_tracking.pcb_type to the board_pcbs.id but this was kind of an envolving project and this is how it is now ;)

 

What I am trying to do is Join board_tracking to board_pcbs so that it will show the sap_pn in the results based on pcb_entries.type = board_pcbs.pcb_type

 

This is how my query looks:

 

SELECT T1.type, T2.sap_pn, COUNT(*) FROM board_tracking AS T1 LEFT JOIN board_pcbs AS T2 ON (T1.type = T2.pcb_type) WHERE T1.date_entered >= '2007-05-28 00:00:01' AND T1.date_entered <= '2007-05-28 23:59:59'GROUP BY T1.type

 

It returns NULL for sap_pn and I am not sure why.  I am assuming I am doing something wrong :)

 

T1.type    | T2.sap_pn  |  Count(*)

---------------------------------------

Type1      |  NULL  | 2

---------------------------------------

Type2      | NULL   | 1

---------------------------------------

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For the data listed, the query's dates are out of their range.

 

mysql> SELECT T1.type, T2.sap_pn, COUNT(*) FROM board_tracking AS T1 LEFT JOIN board_pcbs AS T2 ON (T1.type =
T2.pcb_type) WHERE T1.date_entered >= '2007-05-28 00:00:01' AND T1.date_entered <= '2007-05-28 23:59:59' GROUP
BY T1.type;
Empty set (0.00 sec)

mysql> SELECT T1.type, T2.sap_pn, COUNT(*) FROM board_tracking AS T1 LEFT JOIN board_pcbs AS T2 ON (T1.type =
T2.pcb_type) GROUP BY T1.type;
+--------+-------------+----------+
| type   | sap_pn      | COUNT(*) |
+--------+-------------+----------+
| Type 1 | 29-23032-02 |        2 |
| Type 2 | 29-30230-01 |        1 |
+--------+-------------+----------+
2 rows in set (0.00 sec)

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