從SQL表中選擇行，從另一個表中選擇5行

Question

我有三個這樣的SQL Server表

我需要categories from LS_categoires where nodeid = 183選擇categories from LS_categoires where nodeid = 183並select only 5 files from LS_files與每個類別相關的select only 5 files from LS_files中select only 5 files from LS_files

如果我有兩個與node 183有關的類別，結果應該是10 rows嗎？

Answer 1

嘗試這個：

  SELECT
  *  
FROM LS_Categories c 
INNER JOIN
( 
   SELECT 
     *, ROW_NUMBER() OVER(PARTITION BY catid
                          ORDER BY item_id ASC) rownum
   FROM LS_ItemTypes
) l  ON c.catid = l.catid
    AND l.rownum <= 5
INNER JOIN LS_Files f ON l.item_id = f.id
where c.nodeid = 183;

這將為每個類別選擇第一個文件。