Question

我有一个很大的问题，我不知道发生了什么。这是我的

table1

+-----+-----------------------+--------------+
| id  | invoice_number | invoice_date |
+-----+-----------------------+--------------+
|  12 | 12536801244    | 2009-09-23   |
|  38 | 12585302890    | 2009-11-18   |
|  37 | 12584309829    | 2009-11-16   |
| 123 | 12627605146    | 2010-01-06   |
| 191 | 12663105176    | 2010-02-16   |
+-----+-----------------------+--------------+

这是我的第二个

table2

+-----+-----------------------+--------------+
| id  | invoice_number | invoice_date |
+-----+-----------------------+--------------+
|  12 | 1t657801244    | 2009-09-23   |
|  20 | 12585302890    | 2009-11-18   |
|  37 | 1ss58430982    | 2009-11-16   |
| 103 | 12627605146    | 2010-01-06   |
| 121 | 12346310517    | 2010-02-16   |
+-----+-----------------------+--------------+

我想要的是，我得到的所有invoice_numbers都不在 table2

这是我的SQL查询。

select t2.invoice_number FROM table1 t1
JOIN table2 t2 ON t2.invoice_number != t1.inovice_number;

但是我得到了不同的结果。任何机构SQL代码有什么问题？

Answer 1

你为什么不试试：

Select * from Table1
Where Table1.invoice_number NOT IN (select invoice_number from Table2)

Answer 2

您可以使用LEFT JOIN。

SELECT t1.invoice_number 
FROM   table1 t1
       LEFT JOIN table2 t2 ON t2.invoice_number = t1.inovice_number
WHERE  t2.invoice_number IS NULL

Answer 3

性能方面，您可以使用Left Join或Not EXIST

尝试使用左连接

Select t2.invoice_number 
FROM table1 t1
LEFT JOIN table2 t2 ON 
          t2.invoice_number = t1.inovice_number AND
          t2.invoice_number IS NULL;

尝试不存在

Select t2.invoice_number
FROM table1 t1 Where Not Exist 
  (
   SELECT NULL 
   FROM table2 t2 
   WHERE  t2.invoice_number = t1.inovice_number
  )

尝试使用Not IN

Select t2.invoice_number 
FROM table1 t1
Where t1.inovice_number NOT IN
(
 SELECT t2.inovice_number
 FROM table2 t2
)

Answer 4

为什么不使用where not exists？

SELECT * 
FROM table1 t1
WHERE NOT EXISTS (SELECT * FROM table2 t2 WHERE t1.invoice_number = t2.invoice_number)

Answer 5

这不是查询您要查找内容的正确方法。

你可能需要这样的东西：

select invoice_number from table2 
where invoice_number not in (select invoice_number from table1)

Answer 6

select * from table1 where invoice_number NOT EXISTS (select invoice_number FROM table2 WHERE  table1.invoice_number = table2.invoice_number);

Answer 7

select t2.id FROM table1 as t1
INNER JOIN table2 as t2 ON t2.id != t1.id;

mysql不相等是行不通的

7 个答案: