Question

我每行都有三个字段，我想将它们串联起来，并按升序排列：

select * concat(field1, field2, field3) AS result
from tbl

我的数据是：

field1, field2, field3
   7       2       9
   4       7       8
   6       3       2

预期结果是：

field1, field2, field3   result
  7       2       9       279
  4       7       8       478
  6       3       2       236

我该怎么做？

Answer 1

Use LEAST ,GREATEST function technically

   SELECT field1, field2, field3,
   concat(LEAST(field1,field2,field3), 
   (field1 + field2 + field3) - (GREATEST(field1,field2,field3)+
   LEAST(field1,field2,field3)),
   GREATEST(field1,field2,field3)
   ) 
   from tbl

Answer 2

You can try GROUP_CONCAT approach. It can be extended to any number of columns:

CREATE TABLE testdata(id INT PRIMARY KEY, field1 INT, field2 INT, field3 INT);
INSERT INTO testdata (id, field1, field2, field3) VALUES
(1, 7, 2, 9),
(2, 4, 7, 8),
(3, 6, 3, 2);

SELECT testdata.id, field1, field2, field3, GROUP_CONCAT(rtc.fields ORDER BY fields SEPARATOR '') AS fields_sorted
FROM testdata
INNER JOIN (
    SELECT id, field1 AS fields FROM testdata UNION ALL
    SELECT id, field2 AS fields FROM testdata UNION ALL
    SELECT id, field3 AS fields FROM testdata
) AS rtc ON testdata.id = rtc.id
GROUP BY testdata.id, field1, field2, field3;

Output:

+----+--------+--------+--------+---------------+
| id | field1 | field2 | field3 | fields_sorted |
+----+--------+--------+--------+---------------+
|  1 |      7 |      2 |      9 | 279           |
|  2 |      4 |      7 |      8 | 478           |
|  3 |      6 |      3 |      2 | 236           |
+----+--------+--------+--------+---------------+

Answer 3

请尝试解决方案，尽管我尚未测试过。您只需稍作修改，就能实现您想要的。任何改进，请在评论中提及。

select id, concat(MIN_VAL, MIDDLE_VAL, MAX_VAL) 
from
   ( SELECT ID,
        (CASE
            WHEN field1 >= field2 AND field1 >= field3 THEN field1
            WHEN field2 >= field1 AND field2 >= field3 THEN field2 
            WHEN field3 >= field1 AND field3 >= field2 THEN field3
            ELSE  field1 END) MAX_VAL

    ,Case When field1 < field2 And field1 < field3 Then field1 
                When field2 < field1 And field2 < field3 Then field2 
                Else field3
                End As MIN_VAL
    ,Case When (field1 >= field2 And field1 <= field3) OR  (field1 <= field2 And field1 >= field3) Then field1 
                When (field2 >= field3 And field2 <= field1) OR (field2 <= field3 And field2 >= field1)Then field2
                 WHEN (field3 >= field1 AND field3 <= field2) OR  (field3 <= field1 AND field3 >= field2) THEN field3 
                Else field1
                End As MIDDLE_VAL

       From table
) int_pass

Answer 4

一种更优雅的解决方案是利用本机json_extract函数根据其键升序提取值。

select json_extract('{"10":10, "5": 5}', '$.*'); // [5, 10]

使用json_object函数构建json对象，并为键和值使用相同的字段
使用json_extract
将[，,和]替换为空白

select json_extract( json_object(f1, f1, f2, f2, f3, f3), '$.*' )

假设f1 = 5, f2 = 4 and f3 = 1，您将得到[1,4,5]

现在您可以使用替换字符替换不需要的字符

select replace( replace( replace( json_extract( json_object(f1, f1, f2, f2, f3, f3), '$.*' ), '[', ''), ']', ''), ', ', '') from t;

Answer 5

假设，您要按字段field2，field1，field3的顺序将列作为字符串串联

尝试：

select * ,concat(field2,field1,field3) as "result" from tbl;

Answer 6

您可以将MySQL的CONCAT功能用作：

SELECT *, CONCAT(field1, field2, field3) AS result from tbl;

如何在MYSQL中对列进行排序

6 个答案: