Mysql 在FK中使用空值联接表_Mysql_Join

Mysql 在FK中使用空值联接表

mysql join

Mysql 在FK中使用空值联接表,mysql,join,Mysql,Join,我想从三个表中选择一些值，这些表由外键关联包含外键的表在该FK中可能有空值当我从三个表中选择时，我不会得到FK为空的行例如，这些是我的表格：表1（boninterne）： +---------+-----------+----------+----------+ | num | date | codePers | codeDept | +---------+-----------+----------+----------+ |1 |12/10/2012

我想从三个表中选择一些值，这些表由外键关联

包含外键的表在该FK中可能有空值

当我从三个表中选择时，我不会得到FK为空的行

例如，这些是我的表格：

表1（boninterne）：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

表2（人员）：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

表3（部门）：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

这是我提出的问题：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

我想要的表格是：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

但我真正得到的是：

+---------+-----------+----------+----------+
|   num   |   date    | codePers | codeDept |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  2       |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  4       |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  12      |  2       |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  3       |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  1       |  2       |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  3       |
+---------+-----------+----------+----------+

+---------+-----------+----------+
|codePers |prenomPers | nomPers  |
+---------+-----------+----------+
|1        |AA         +  ZZ      |
+---------+-----------+----------+
|4        |BB         |  WW      |
+---------+-----------+----------+
|3        |CC         |  XX      |
+---------+-----------+----------+
|12       |DD         |  VV      |
+---------+-----------+----------+

+---------+-----------+
|codeDept |libDept    |
+---------+-----------+
|2        |DEPT A1    +
+---------+-----------+
|3        |DEPT B1    |
+---------+-----------+

SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne, personnel, departement
WHERE boninterne.codePers = personnel.codePers
AND boninterne.codeDept = departement.codeDept

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|1        |12/10/2012 +  NULL    |  DEPT A1 |
+---------+-----------+----------+----------+
|2        |12/10/2012 |  NULL    |  NULL    |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|4        |12/10/2012 |  BB WW   |  NULL    |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|6        |12/10/2012 |  CC XX   |  NULL    |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|8        |12/10/2012 |  NULL    |  DEPT B1 |
+---------+-----------+----------+----------+

+---------+-----------+----------+----------+
|   num   |   date    | nom      | libDept  |
+---------+-----------+----------+----------+
|3        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+
|5        |12/10/2012 |  DD VV   |  DEPT A1 |
+---------+-----------+----------+----------+
|7        |12/10/2012 |  AA ZZ   |  DEPT A1 |
+---------+-----------+----------+----------+

我必须在查询中更改什么才能得到该表？？？

您的结果是正确的，因为您使用的是内部联接。您可以通过使用正确的联接语法并改为使用

左外部联接来解决此问题：
SELECT num, date, CONCAT(prenomPers,' ',nomPers) AS nom, libDept 
FROM boninterne
left outer join personnel
    on boninterne.codePers = personnel.codePers
left outer join departement
     on boninterne.codeDept = departement.codeDept;

这将保留第一个表中的所有内容，即使没有匹配项。
请使用ANSI 1992联接。在那之后你会更清楚。@Sebas你所说的ansi1992连接是什么意思？请参阅，在第179页（以后）中查找“查询表达式”他指的是显式的连接。。。关于
语法。