Question

I have 3 tables with same columns, I need to get count of rows with respect to packname column for all the 3 tables.

Below are the input and output table data.

TABLE 1     

CALLERID    PACKANME    
9882000342  DOC 
9882000560  DOC 
9882000945  RAJ 
9882002655  CAR 
9882003225  CAR 

TABLE 2     

CALLERID    PACKANME    
9882000342  DOC 
9882000560  DOC 
9882000945  RAJ 
9882002655  CAR 

TABLE 3     

CALLERID    PACKANME    
9882000342  DOC 
9882000560  DOC 
9882000945  RAJ 

OUTPUT      

PACKNAME    COUNT TAB2  COUNT TAB3
DOC            2                2
RAJ            1                1
CAR            1                0

I have tried below query and stopped here, I beleive we have use pivot to get the desired output but unable to do that.Please help me out.

Select 'TableA' as 'TableName',tbla.packname as Ptype,Count(tbla.num) as MobCnt from tbla
Group By tbla.packname 
Union all
Select 'TableB' as 'TableName',tblb.packname  as Ptype,Count(tblb.num)as MobCnt from tblb
Group By tblb.packname 
Union all
Select 'TableC' as 'TableName',tblc.packname  as Ptype,Count(tblc.num)as MobCnt from tblc
Group By tblc.packname 

Answer 1

First off, generate a list of distinct packnames across all tables. Then outer join a count of each table onto this. This way, you can read zero counts correctly.

SELECT
     list.packname,
     ISNULL(A.ACnt, 0) AS Tblacount,
     ISNULL(B.BCnt, 0) AS Tblbcount,
     ISNULL(C.CCnt, 0) AS Tblccount
FROM
    (
    SELECT packname FROM tbla
    UNION
    SELECT packname FROM tblb
    UNION
    SELECT packname FROM tblc
    ) list
    LEFT JOIN
    (
    Select tbla.packname as Ptype, Count(*) as ACnt from tbla
    Group By tbla.packname
    ) A ON list.packname = A.Ptype
    LEFT JOIN
    (
    Select tblb.packname as Ptype, Count(*) as BCnt from tblb
    Group By tblb.packname
    ) B ON list.packname = B.Ptype
    LEFT JOIN
    (
    Select tblc.packname as Ptype, Count(*) as CCnt from tblc
    Group By tblc.packname
    ) C ON list.packname = C.Ptype