Inner left join to get value on previous date

Question

I am trying to get value of GR2 on previous date TabDate in following query:

    DECLARE @ShN money=STRLOG.dbo.fn_VarValue('ShN') 
    DECLARE @ShNs money=STRLOG.dbo.fn_VarValue('ShNs') 
    DECLARE @ShNN money=STRLOG.dbo.fn_VarValue('ShN')     +STRLOG.dbo.fn_VarValue('ShNs') 
    DECLARE @ShD money=STRLOG.dbo.fn_VarValue('ShD') 

    SELECT sum(
        CASE 
            WHEN ttab.GR2='33' 
            THEN 
                CASE 
                -- Randam ar sekianti diena sventes         
                WHEN tholy.[ID] IS NOT NULL
                THEN @ShN

                ELSE @ShN 
                END
            WHEN ttab.GR2='3' 
            THEN 
                CASE 
                -- Randam ar sekianti diena sventes         
                WHEN tholy.[ID] IS NOT NULL
                THEN @ShNs
                -- Randam ar tai pirma 3-cios pamainos diena
                WHEN tprev.GR2='3'
                THEN @ShNN

                ELSE @ShNs 
                END
            ELSE 
                CASE 
                -- Randam ar sekianti diena sventes         
                WHEN tholy.[ID] IS NOT NULL
                THEN @ShD-60
                ELSE @ShD 
                END
        END
        )/60, 
        ttab.EmplCodeID
        FROM tbl_TabelWHrs          INNER JOIN tbl_Tabel ttab           
             ON tbl_TabelWHrs.TabWHrsID = ttab.TabWHrsID
        LEFT JOIN tbl_Holidays tholy            
             ON [HolidayDate]=DATEADD("DAY",1,[TabDate])
        LEFT JOIN  tbl_Tabel tprev          
             ON ttab.[EmplCodeID]=tprev.[EmplCodeID]            
             AND [ttab.TabDate]=DATEADD("DAY",-1,[tprev.TabDate])
        WHERE (tbl_TabelWHrs.TabMon='2014.12' AND ttab.EmplCodeID='7040023' AND ttab.GR2 is not null)
        GROUP BY ttab.EmplCodeID;

What I get on execution is 2 errors:

---

Msg 207, Level 16, State 1, Line 47 Invalid column name 'ttab.TabDate'. Msg 207, Level 16, State 1, Line 47 Invalid column name 'tprev.TabDate'.

---

Its something wrong with "LEFT JOIN tbl_Tabel tprev". Error rises on fields in line "AND [ttab.TabDate]=DATEADD("DAY",-1,[tprev.TabDate])". What I do wrong here?

Answer 1

the problem here is use have used square bracket before the alias name and ended it after the column name so [tprev.TabDate] will be considered as a column, Alias name is escaped here.

change the condition like this.

.....
LEFT JOIN  tbl_Tabel tprev          
     ON ttab.[EmplCodeID]=tprev.[EmplCodeID]            
     AND ttab.[TabDate]=DATEADD("DAY",-1,tprev.[TabDate])  -- here
....