SQL Abfrage, Zählen von n Datensätzen aus 2. Tabelle

[omata]

SQL-Code:

SELECT IssueID, Name, 
       CASE WHEN (SELECT COUNT(*) 
                  FROM TB_IssueAttachetFiles 
                  WHERE FK_IssueID = i.IssueID) > 0 
          THEN 'Yes' 
          ELSE NULL
       END Attachment
FROM tb_issues i

da du die genaue Anzahl ja nicht benötigst...

SQL-Code:

SELECT IssueID, Name, 
       CASE WHEN EXISTS (SELECT *
                         FROM TB_IssueAttachetFiles 
                         WHERE FK_IssueID = i.IssueID)
          THEN 'Yes' 
          ELSE NULL
       END Attachment
FROM tb_issues i

oder auch...

SQL-Code:

SELECT i.IssueID, i.Name, COALESCE('Yes (' + a.anzahl + ')', '') AS Attachment
FROM tb_issues i
LEFT JOIN (SELECT FK_IssueID, COUNT(*) AS anzahl
           FROM TB_IssueAttachetFiles
           GROUP BY FK_IssueID) a
  ON i.IssueID = a.FK_IssueID