Why is this SQL query returning this result? - sql

Question

Can anyone tell me why this sql query is returning this result.
SELECT
M.MatterNumber_Id, M.MatterNumber, M.MatterName,
ISNULL(MP.Role_Cd, 'No Primary') AS PrimaryRole,
ISNULL(E.Name, 'No Primary') AS PrimaryName,
ISNULL(C.CommNumber, 'l.w#abc.ca;m.j#abc.com') AS Email
FROM
Matter M
LEFT OUTER JOIN
MatterPlayer MP ON M.MatterNumber_Id = MP.MatterNumber_Id AND
MP.Role_Cd IN ('Primary Lawyer', 'Primary Staff Member') AND
MP.EndDate IS NULL
LEFT OUTER JOIN
Entity E on MP.Entity_EID = E.Entity_EID
LEFT OUTER JOIN Communication C on MP.Entity_EID = C.Entity_EID AND
C.CommunicationType_Cd = 'Email'
LEFT OUTER JOIN
MatterExposure ME on M.MatterNumber_Id = ME.MatterNumber_Id AND
ME.AssessedDate > '7/10/2014' AND
ME.Currency_CD IS NOT NULL
WHERE
M.MatterStatus_Cd = 'Active' AND
ME.AssessedDate IS NULL AND
M.Matter_Cd in
(SELECT
rpl.Type_CD
FROM
RuleProfile_Tabs rpt
INNER JOIN
RuleProfile_LookupCode rpl ON rpt.RuleProfile_ID = rpl.RuleProfile_ID
WHERE
tab_id = 1034 AND Caption LIKE 'Reportable Matter%')
ORDER BY
Email, M.MatterName
But When i see the results I check one of the records returned and it should not have been returned.
One of the results returned:
Bailey, Richard
In the db i check the values in the tables it should not have been returned because Currency_CD is null and in the sql it states currency_cd is not null. Also the assessed date is AFTER 7/10/2014
Table Values:
MatterStatus_CD:
Active
AssessedDate:
7/24/2014
Currency_CD:
NULL
EndDate:
NULL

Answer 1

Where clauses are used for filtering, not the join clause. Every JOIN should have an ON. Here's a head start.
Select M.MatterNumber_Id, M.MatterNumber, M.MatterName,
IsNull(MP.Role_Cd, 'No Primary') as PrimaryRole,
IsNull(E.Name, 'No Primary') as PrimaryName,
IsNull(C.CommNumber, 'l.w#abc.ca;m.j#abc.com') as Email
From Matter M
Left Outer Join MatterPlayer MP on M.MatterNumber_Id = MP.MatterNumber_Id
Left Outer Join Entity E on MP.Entity_EID = E.Entity_EID
Left Outer Join Communication C on MP.Entity_EID = C.Entity_EID
Left Outer Join MatterExposure ME on M.MatterNumber_Id = ME.MatterNumber_Id
Where M.MatterStatus_Cd = 'Active'
AND ME.AssessedDate is Null
and M.Matter_Cd in (select rpl.Type_CD
from RuleProfile_Tabs rpt
inner join RuleProfile_LookupCode rpl on rpt.RuleProfile_ID = rpl.RuleProfile_ID
where tab_id = 1034 AND Caption like 'Reportable Matter%')
and MP.Role_Cd In ('Primary Lawyer', 'Primary Staff Member')
and MP.EndDate is Null
and ME.AssessedDate > '7/10/2014'
and ME.Currency_CD IS NOT NULL
and C.CommunicationType_Cd = 'Email'
Order by Email, M.MatterName

Answer 2

You are LEFT JOINing MatterExposure onto Matter. Your Me.Currency_CD IS NOT NULL criteria in the LEFT JOIN's ON statement is only saying, "don't join to records where Currency_CD is null..." but because this is a left join, none of your Matter table's records are lost in the join. So when you ask for Currency_CD you will get NULL.
To remove records from your query where Currency_CD is null in the MatterExposure table you will either need to specify Currency_CD IS NOT NULL in your where statement (instead of your join) or will need to use an INNER JOIN to your MatterExposure table.

Answer 3

It is because this join is a LEFT OUTER JOIN. If you want to enforce this join make it an inner join. Or move that check to the WHERE clause.