Help Understanding Nested INNER JOIN

[Noob]

Hi,

I am having a hard time wrapping my head around this Query. I need to be able to explain in plain english what it is doing.

UPDATE     [a Cust Data]
INNER JOIN (G_N_TRANS 
INNER JOIN [REF Mail NIPPS] 
ON         G_N_TRANS.N_P_ID = [REF Mail NIPPS].NAB) 
ON         [a Cust Data].NPI = G_N_TRANS.NPI_ID 
SET        [a Cust Data].[Mail/Retail] = "Mail" 
WHERE      ((( 
                                            [a Cust Data].NPI) IS NOT NULL 
                      AND        ( 
                                            [a Cust Data].NPI)<>"")));

I think that SQL is going to Start by JOINING the 2nd JOIN1st. So if that is TRUE then. The 2nd INNER JOIN is going to use TABLEs"REF Mail NIPPS" & "G_N_TRANS" & what is throwingme is that the FIELD NAMES are different, but the data TYPE is the same (integers).This is making smoke come outta my ears because I thought that INNER JOINS hadto be "equi JOINs"

[orange]

I'm not sure where that specific query originated, but here are some links that may help with multiple Joins.

http://stackoverflow.com/questions/1...e-involved-sql
https://technet.microsoft.com/en-us/...=sql.105).aspx
http://stackoverflow.com/questions/9...ple-inner-join

[Bulzie]

Field names can be different(althought not the best setup), datatypes need to be the same on joins.

The joins are
[a Cust Data].NPI = G_N_TRANS.NPI_ID
G_N_TRANS.N_P_ID = [REF Mail NIPPS].NAB)

You can visualize this in the Query Designer. Create new Query, add the 3 tables. Link those tables on those fields and add the Where conditions. Run it to see if data right. Then look at it in SQL code and see how it looks.

[Noob]

Hi & THANKS!!!

Field names can be different(althought not the bestsetup), datatypes need to be the same on joins.

Yeah I agree not the BEST, but it is what they got. I assumeit is because of the original design of the DBs. That was really killing me tho. Again thanks so much.

P.S. This is also helpful thanks for sharing:

You can visualize this in the Query Designer. Create new Query, add the 3 tables. Link those tables on those fields and add the Where conditions. Run it to see if data right. Then look at it in SQL code and see how it looks.

[Noob]

One more quick question. What is executed 1st? Would theJOIN in the parentheses be done 1st?