来自两个不同表的COUNT个

Question

This is a funky question, I know this. And maybe it's all because I'm really tired.

Now, don't blame the design - it is flawed, but nothing I can do anything about, ok?

• Two tables, linked by a id-field.
• First table contains positions in a warehouse (table P)
• Second table contains articles stored on each position in the warehouse (table PA)
• ALL positions in the warehouse are present in the P-table (> 5000 records)
• Each position could contain more than one article
• The are positions in the P-table not present in the PA-table

The count from positionarticles PLUS the positions not present in positionarticles.

Is there really no better way than this utter stupidity?:

SELECT SUM(row)
FROM
(
  SELECT COUNT(*) row
  FROM PA
  UNION
  SELECT COUNT(*)
  FROM P
  WHERE ID NOT IN
    (
      SELECT P_ID
      FROM PA
    )
) as rowcounter

Sample data

Table P:

ID   Name
1    A01
2    A03
3    B01  *
4    B02  *

Table PA:

ID   P_ID   A_ID
1    1      201  *
2    1      202  *
3    1      203  *
4    2      205  *

And the count returned is 6 => 4 rows from PA + 2 rows (P_IDs not present in PA). Rows counted are star-marked (*).

Answer 1

Try this:

SELECT P.ID, COUNT(PA.ID) noOfArticles
FROM P 
LEFT JOIN PA ON P.ID = PA.P_ID 
GROUP BY P.ID