MySQL 将多个表中的行组合成一行

Question

我正在尝试将数据库中两个不同表的两列合并为一列。

cust_tbl(表 1):

JL_JOB_NO | 
-----------
1         |  
2         |

项目(表 2):

prjID     | 
-----------
3         |  
4         |

我希望我的输出是:

new       | 
-----------
1         |  
2         |
3         |
4         |

我尝试过:

SELECT 'JL_JOB_NO' AS 'new'
FROM 'cust_tbl'
UNION
SELECT 'prjID' as 'new'
FROM 'projects';

Answer 1

使用反引号 (`) 代替单引号(或直接删除它们):

试试这个:

SELECT `JL_JOB_NO` AS `new`
FROM `cust_tbl`
UNION
SELECT `prjID` as `new`
FROM `projects`;

或者只是:

SELECT JL_JOB_NO AS new
FROM cust_tbl
UNION
SELECT prjID as new
FROM projects;

Side note: Back ticks are to be used for table and column identifiers, but are only necessary when the identifier is a MySQL reserved keyword, or when the identifier contains whitespace characters or characters beyond a limited set it is often recommended to avoid using reserved keywords as column or table identifiers when possible, avoiding the quoting issue.

在以下情况下需要反勾号:

SELECT id, `my name`, `another field` , `field,with,comma`