SQL query works even with wrong syntax - sql

Question

I am running a SQL query in stored procedure which is like following
SELECT
t1.id,t2.Name
FROM
table1 t1 , table2 t2 ,table2 t3,table4 t4
WHERE
t1.id=t3.t4.id
this query gets executed on SQL server 2008 when its compatible with SQL server 2000 but if we turn OFF the compatibility with SQL server 2000 then this Query gives syntax error which is expected.
Can some one help me to understand why this is happeneing ? thanks in advance
Original query:
SELECT
ConfigID , LocationDesc + '-' + LOBTeamDesc LocLOBTeamSource
FROM Config CONFIG , Location_LOBTeam LOCLOB , Location LOC , LOBTeam LOB, System SRC
WHERE CONFIG.LocationLOBTeamID = LOC.LOB.LocationLOBTeamID
AND CONFIG.SourceSystemID = SRC.SystemID
AND LOCLOB.LocationID = LOC.LocationID
AND LOCLOB.LOBTeamID = LOB.LOBTeamID
AND (GETDATE() BETWEEN CONFIG.effectiveDate AND CONFIG.EndDate
OR CONFIG.EndDate IS NULL)
ORDER BY
LOC.LocationCode

Answer 1

I think that original query, with current standard join syntax applied would be this:
SELECT
ConfigID
, LocationDesc + '-' + LOBTeamDesc LocLOBTeamSource
FROM Config CONFIG
INNER JOIN Location_LOBTeam LOCLOB
ON CONFIG.LocationLOBTeamID = LOCLOB.LocationLOBTeamID
INNER JOIN Location LOC
ON LOCLOB.LocationID = LOC.LocationID
INNER JOIN LOBTeam LOB
ON LOCLOB.LOBTeamID = LOB.LOBTeamID
INNER JOIN [System] SRC
ON CONFIG.SourceSystemID = SRC.SystemID
WHERE (GETDATE() BETWEEN CONFIG.effectiveDate AND CONFIG.EndDate
OR CONFIG.EndDate IS NULL)
ORDER BY
LOC.LocationCode
Perhaps this will help.
+EDIT
"System" as a table name, could that be a problem? Suggest you try it as [System]
+EDIT2
The original is given with this: LOC.LOB.LocationLOBTeamID but that appears to be an error as there is an alias LOCLOB

Answer 2

I think below post from msdn answers this issue Compatibility Levels and Stored Procedures
in the above post the point number 3 under section "Differences Between Compatibility Level 80 and Level 90" states "WHEN binding the column references in the ORDER BY list to the columns defined in the SELECT list, column ambiguities are ignored and column prefixes are sometimes ignored. This can cause the result set to return in an unexpected order."
on my database I am using compatibility level 80 i.e 2000 thats why it runs smoothly with the given syntax but when I remove this compatibility and make it to 100 i.e. 2008/R2 script gives syntax error which is expected