Question

我正在学习数据库查询，我遇到了一种情况，我根据某些条件得到了字段

    select brandname 
    from shopping_men_women_fashion.shoppingbrandmaster 
    where shoppingbrandmaster.brandid =clothing.brandid

抛出错误

 missing FROM-clause entry for table clothing.brandid

这个错误是什么？

Answer 1

您错过了加入clothing Table

SELECT shoppingbrandmaster.brandname
FROM   shopping_men_women_fashion.shoppingbrandmaster,
       clothing
WHERE  shoppingbrandmaster.brandid = clothing.brandid

OR

SELECT shoppingbrandmaster.brandname
FROM   shopping_men_women_fashion.shoppingbrandmaster
       JOIN clothing
         ON shoppingbrandmaster.brandid = clothing.brandid

Answer 2

您可以使用表别名和USING简化语法：

SELECT s.brandname
FROM   shopping_men_women_fashion.shoppingbrandmaster s
JOIN   shopping_men_women_fashion.clothing            c USING (brandid);

我假设你的第二个表也存在于模式shopping_men_women_fashion中。如果对一个表进行模式限定是有意义的，那么对另一个表进行模式限定是有意义的。

（此示例中未引用c的列别名clothing，可以将其删除。）

缺少postgresql中表的FROM子句条目

2 个答案: