使用where子句会导致无效的列名错误

Question

I am using SQL Server 2012.

I have written the query below which works fine apart from when I include the last line 'where NomDiff <> 0'.

It tells me NomDiff is an invalid column name. I don't understand why and don't know how to get the query to return only rows where the nomDiff is not equal to zero?

;with pf as
(
    select Name, Sedol, Nominal from tblTempPLF 
    where FundCode = 'CSGE'
), pc as
(
    select Name, Sedol, Nominal from tblTempPCF 
    where FundCode = 'BTCM'
)
select coalesce(pf.Name, pc.Name) Name, coalesce(pf.Sedol, pc.Sedol) Sedol, 
isnull(pf.Nominal,0) PfNom, isnull(pc.Nominal,0) PcNom, isnull(pf.Nominal,0) - isnull(pc.Nominal,0) NomDiff
from pf full outer join pc on pf.Sedol = pc.Sedol
where NomDiff <> 0 

Answer 1

Using APPLY VALUES is a good way of not having to use a subquery, or another CTE:

WITH    pf
AS ( SELECT
      Name ,
      Sedol ,
      Nominal
      FROM tblTempPLF
      WHERE FundCode = 'CSGE'
    ),
pc
AS ( SELECT
      Name ,
      Sedol ,
      Nominal
      FROM tblTempPCF
      WHERE FundCode = 'BTCM'
    )
  SELECT
      Name = COALESCE(pf.Name, pc.Name),
      Sedol = COALESCE(pf.Sedol, pc.Sedol),
      PfNom = ISNULL(pf.Nominal, 0),
      PcNom = ISNULL(pc.Nominal, 0),
      NomDiff = Nom.Diff
  FROM pf
  FULL OUTER JOIN pc
  ON  pf.Sedol = pc.Sedol
  CROSS APPLY(VALUES(ISNULL(pf.Nominal, 0) - ISNULL(pc.Nominal, 0))) AS Nom(Diff)
  WHERE Nom.Diff <> 0;

Answer 2

You can't use a previously defined alias in the where clause. Use the calculation instead.

select coalesce(pf.Name, pc.Name) Name, 
coalesce(pf.Sedol, pc.Sedol) Sedol,   
isnull(pf.Nominal,0) PfNom, isnull(pc.Nominal,0) PcNom, 
isnull(pf.Nominal,0) - isnull(pc.Nominal,0) NomDiff
from pf full outer join pc on pf.Sedol = pc.Sedol
where isnull(pf.Nominal,0) - isnull(pc.Nominal,0)<> 0

Answer 3

You can't use the alias for the column in the WHERE since you are creating it in the SELECT , change to:

WHERE isnull(pf.Nominal,0) - isnull(pc.Nominal,0) <> 0

Or you can use a subquery/cte to make the alias available to an outer query that references it.

The reason for this is that WHERE is actually evaluated prior to SELECT , the optimizer filters out rows before worrying about which fields to return.

Answer 4

Just add another cte so you can use the alias

;with pf as
(
    select Name, Sedol, Nominal from tblTempPLF 
    where FundCode = 'CSGE'
), pc as
(
    select Name, Sedol, Nominal from tblTempPCF 
    where FundCode = 'BTCM'
), anotherOne as /* add another cte */
(
    select 
        coalesce(pf.Name, pc.Name) Name, 
        coalesce(pf.Sedol, pc.Sedol) Sedol, 
        isnull(pf.Nominal,0) PfNom, 
        isnull(pc.Nominal,0) PcNom, 
        isnull(pf.Nominal,0) - isnull(pc.Nominal,0) NomDiff
    from pf full 
    outer join pc 
        on pf.Sedol = pc.Sedol
)
select *
from anotherOne
where NomDiff <> 0 

Answer 5

Since you are already using CTE , it would be easier to just wrap that outer query as another CTE and then filter out the NomDiff (alias for the calculated column). Alias does not scope within the same select statement, so in order to use an Alias directly, you would need to wrap that either in a subquery or a CTE . Otherwise, you could also directly use the calculation in the where clause like others have suggested here.

;WITH pf
AS (
    SELECT NAME
        ,Sedol
        ,Nominal
    FROM tblTempPLF
    WHERE FundCode = 'CSGE'
    )
    ,pc
AS (
    SELECT NAME
        ,Sedol
        ,Nominal
    FROM tblTempPCF
    WHERE FundCode = 'BTCM'
    )
    ,calc
AS (
    SELECT coalesce(pf.NAME, pc.NAME) NAME
        ,coalesce(pf.Sedol, pc.Sedol) Sedol
        ,isnull(pf.Nominal, 0) PfNom
        ,isnull(pc.Nominal, 0) PcNom
        ,isnull(pf.Nominal, 0) - isnull(pc.Nominal, 0) NomDiff
    FROM pf
    FULL OUTER JOIN pc ON pf.Sedol = pc.Sedol
    )
SELECT *
FROM calc
WHERE NomDiff <> 0