將table id從一列複製到另一列，其中列數據匹配表

Question

我有兩個表，Fruits和Meals，Meals中的其中一列是varchar（100），其中包含水果。我正在改變這個，以便 這個列代替水果表中的水果的ID，我想通過比較這兩個表並從水果列匹配的水果表中抓取ID 來設置它。

Table: Fruits 
id | fruit 
1 apple 
2 banana 
3 orange 

Table: Meals 
id | Meal | Fruit 
1 xxxx apple 
2 xxxx apple 
3 xxxx orange 
4 xxxx banana 
5 xxxx orange 
6 xxxx orange 
7 xxxx apple 

我試過以下腳本，但出現以下錯誤。

Update product_attribute set control_caption = 
(
    Select DISTINCT T1.control_caption_id from control_caption T1 
    INNER Join product_attribute T2 
    On T1.control_caption = T2.control_caption 
    Where T1.control_caption = T2.control_caption 
) 

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression. 

Answer 1

取決於你的RDBMS，但這應該對SQL Server的工作：

Update pa 
set pa.control_caption = cc.control_caption_id 
From product_attribute pa 
    Join control_caption cc On 
     cc.control_caption = pa.control_caption