将具有右外连接的访问​​查询转换为 sqlite 查询

Posted 2023-02-24

【中文标题】将具有右外连接的访问​​查询转换为 sqlite 查询

【英文标题】：Convert access query with right outer join to sqlite query

【发布时间】：2012-08-24 10:43:06

【问题描述】：

SELECT t13_Literature_Material_Codes.Databank, t13_Literature_Material_Codes.BASE_NUMB, t13_Literature_Material_Codes.BASE_SYMB, t13_Literature_Material_Codes.BASE_CHAR, t13_Literature_Material_Codes.BASE_MOLW, CorrosionRatesInfo.RatesValidFlag FROM CorrosionRatesInfo RIGHT JOIN t13_Literature_Material_Codes ON CorrosionRatesInfo.BASE_NUMB=t13_Literature_Material_Codes.BASE_NUMB;

如何在 sqlite 中进行此查询？我看到人们使用左外连接。请提供使用类似结构的解决方案，然后我的 c++ 程序可以使用简单的解析器过程修改查询字符串。

【参考方案1】：

在 Sqlite 中执行此查询：

SELECT t13_Literature_Material_Codes.Databank, t13_Literature_Material_Codes.BASE_NUMB, 
t13_Literature_Material_Codes.BASE_SYMB, t13_Literature_Material_Codes.BASE_CHAR, 
t13_Literature_Material_Codes.BASE_MOLW, CorrosionRatesInfo.RatesValidFlag FROM 
CorrosionRatesInfo RIGHT OUTER JOIN t13_Literature_Material_Codes ON  
CorrosionRatesInfo.BASE_NUMB=t13_Literature_Material_Codes.BASE_NUMB;

只需添加“RIGHT OUTER JOIN”即可。

【讨论】：

我尝试了“右外连接”，但出现错误：当前不支持右外连接和全外连接

“SELECT t13_Literature_Material_Codes.Databank，t13_Literature_Material_Codes.BASE_NUMB，t13_Literature_Material_Codes.BASE_SYMB，t13_Literature_Material_Codes.BASE_CHAR，t13_Literature_Material_Codes.BASE_MOLW，CorrosionRatesInfo.RatesValidFlag FROM t13_Literature_Material_Codes LEFT JOIN CorrosionRatesInfo上CorrosionRatesInfo.BASE_NUMB = t13_Literature_Material_Codes.BASE_NUMB” 成功了！我交换了表名并将“右连接”更改为“左连接”

【参考方案2】：

用户 UNION 来解决这个问题

举例

SELECT employee.*, department.*
FROM   employee 
       LEFT JOIN department 
          ON employee.DepartmentID = department.DepartmentID
UNION ALL
SELECT employee.*, department.*
FROM   department
       LEFT JOIN employee
          ON employee.DepartmentID = department.DepartmentID
WHERE  employee.DepartmentID IS NULL

是的，see the example on Wikipedia.