Question

我有桌子

table_order
PRODUCT_NAME

下面是我必须查询table_order的SQL，它在输出product_id时非常有效，但我需要它来显示它的名字而不是数字。我需要使用LEFTJOIN修改mySQL以某种方式连接表product_name但我一直收到错误。而不是

99 = 15,99 = 16

我需要

99 = name1,99 = name2

SELECT table_order.order_id, table_order.product_id
              FROM table_order 
              WHERE table_order.order_id=99
              ORDER BY table_order.order_product_id


table table_order
_________________________
order_id  |  product_id |
_________________________
99        |  15         |
99        |  16         |
_________________________

table product_name
___________________________
product_id |  product_name |
___________________________
15         |  name1        |
16         |  name2        |
___________________________

Answer 1

使用

SELECT a.product_id, b.product_name
   FROM table_order AS a LEFT JOIN product_name AS b ON a.product_id = b.product_id
   WHERE a.order_id = '99'
   ORDER BY a.product_id

Answer 2

Select t1.product_id,t2.product_name from table_order as t1
  inner join(
    select * from product_name
  ) as t2
  on t1.product_id = t2.product_name
  where t1.product_id = //some Number

看看是否有效。

Answer 3

如您所说，您需要在product_id上加入表格。

SELECT table_order.order_id, product_name.product_name
FROM table_order 
    INNER JOIN product_name on table_order.product_id = product_name.product_id
WHERE table_order.order_id=99
ORDER BY table_order.product_id

Answer 4

如果您需要输出所有订单，无论该table_order的产品ID是否与product_table有连接，您都需要使用LEFT JOIN。

SELECT o.order_id, p.product_name
   FROM table_order o
      LEFT JOIN product_name p  ON o.product_id = p.product_id  
   ORDER BY o.product_id

但是，如果您只需要获取两个表中存在的所有行，则可以使用INNER JOIN

SELECT o.order_id, p.product_name
   FROM table_order o
      INNER JOIN product_name p  ON o.product_id = p.product_id  
   ORDER BY o.product_id

SQL使用LEFTJOIN连接两个表

4 个答案: