使用分区依据将值插入临时表

Question

If have a temporary table declared as following:

CREATE TABLE #tempKleerkast(
id INT IDENTITY NOT NULL PRIMARY KEY,
IDKleerkastPersoon int,
ID_Persoon int,
rk int
)

Now i wish to fill up the table with the values from an actual table where i want to get the latest (Not Max) record for each person. Therefor i'm using the following query:

      SELECT 
      DISTINCT IDKleerkastPersoon AS Expr1, kk.ID_Persoon,
      ROW_NUMBER() OVER (PARTITION BY kk.ID_Persoon
                            ORDER BY kk.IDKleerkastPersoon DESC) AS rk
      FROM KleerkastPerPersoon kk
      WHERE  kk.ID_Persoon IS NOT NULL AND rk = 1

The problem is where is when i wish to use insert into as following:

      INSERT INTO #tempKleerkast(IDKleerkastPersoon,ID_Persoon,rk)
      SELECT 
      DISTINCT IDKleerkastPersoon AS Expr1, kk.ID_Persoon,
      ROW_NUMBER() OVER (PARTITION BY kk.ID_Persoon
                            ORDER BY kk.IDKleerkastPersoon DESC) AS rk
      FROM KleerkastPerPersoon kk
      WHERE  kk.ID_Persoon IS NOT NULL AND rk = 1

I get the following error: Invalid column name 'rk'. Any idea why he doesn't recognise the column rk?

Note: The column rk is needed further on in the stored procedure. So i can't exclude it.

Answer 1

No, the problem comes before you write the INSERT . Try running just the plain SELECT and you'll see exactly the same error. Logically , WHERE runs before SELECT so you can't refer to aliases introduced by the latter in the former.

This should work:

  INSERT INTO #tempKleerkast(IDKleerkastPersoon,ID_Persoon,rk)
  SELECT IDKleerkastPersoon, ID_Persoon, rk
  FROM (
     SELECT
       IDKleerkastPersoon, kk.ID_Persoon,
          ROW_NUMBER() OVER (PARTITION BY kk.ID_Persoon
                        ORDER BY kk.IDKleerkastPersoon DESC) AS rk
     FROM KleerkastPerPersoon kk
     WHERE  kk.ID_Persoon IS NOT NULL) t
  WHERE rk = 1

(I also removed the DISTINCT since one of the columns listed was also a column listed in the PARTITION BY clause and we're only selecting one row from each partition)