SQL-刪除

Question

我有一個MySQL DATABSE三個表是這樣的：

orders: order_sequence_number, contact_id, date_ordered ... 

orderdetail: order_sequence_number ... 

person: contact_id ... 

我試圖刪除跨有date_ordered值比舊的三個表中的所有行然而，兩年之後，date_ordered字段僅出現在orders表中，但該表通過order_sequence_number和contact_id字段鏈接到其他兩個字段。

所以，我會像有點像這樣：...

SELECT * FROM orders WHERE date_ordered BETWEEN X AND Y 

則與該記錄集

DELETE FROM orderdetail WHERE orderdetail.order_sequence_number IN (THE ABOVE) 

等，爲個人表...但沒有運氣。

在我看來，像某種嵌套子查詢的，但我有困難，瞭解如何做這樣的查詢，並不能讓我圍繞它的繁複，頭...

任何指針將是非常讚賞。

Answer 1

DELETE FROM orderdetail 
WHERE order_sequence_number IN 
(
    SELECT id 
    FROM orders 
    WHERE date_ordered BETWEEN X AND Y 
) 

Answer 2

這就是幾乎你寫的：

DELETE FROM orderdetail WHERE orderdetail.order_sequence_number IN (
    SELECT distinct(order_sequence_number) FROM orders WHERE date_ordered BETWEEN X AND Y 
) 

Answer 3

如果你有一個大表orders，最好使用EXISTS

DELETE FROM orderdetail od 
WHERE EXISTS (SELECT NULL 
       FROM orders o 
       WHERE date_ordered BETWEEN X AND Y 
       and od.order_sequence_number = o.order_sequence_number 
      )