全外连接：Mssql到Mysql的转换

Question

我在MSSQL中有这个查询.. 如何将其转换为MYSQL查询..

CREATE  VIEW DATA_VIEW AS SELECT A.*,B.FIELD_VALUE D1_VALUE,C.FIELD_VALUE D2_VALUE,D.FIELD_VALUE 
C_VALUE FROM DB_DATA A
FULL OUTER JOIN  T_CASE_D1 B ON A.FIELD_ID =B.FIELD_ID AND B.CASE_ID=47758 
FULL OUTER JOIN  T_CASE_D2 C ON A.FIELD_ID =C.FIELD_ID AND C.CASE_ID=47758 
FULL OUTER JOIN  T_CASE_QC D ON A.FIELD_ID =D.FIELD_ID AND D.CASE_ID=47758 
WHERE A.FORM_ID=5 AND IS_ACTIVE='Y'

提前致谢

Answer 1

您的where条款正在将FULL OUTER JOIN转换为LEFT JOIN ，所以您不妨使用它：

CREATE VIEW DATA_VIEW AS 
    SELECT A.*, B.FIELD_VALUE D1_VALUE, C.FIELD_VALUE D2_VALUE, D.FIELD_VALUE AS C_VALUE
    FROM DB_DATA A LEFT JOIN 
         T_CASE_D1 B
         ON A.FIELD_ID = B.FIELD_ID AND B.CASE_ID = 47758 LEFT OUTER JOIN
         T_CASE_D2 C
         ON A.FIELD_ID = C.FIELD_ID AND C.CASE_ID = 47758 LEFT OUTER JOIN
         T_CASE_QC D
         ON A.FIELD_ID  =D.FIELD_ID AND D.CASE_ID = 47758 
    WHERE A.FORM_ID=5 AND IS_ACTIVE = 'Y';

在具有适当维护的外键关系的数据库中很少需要

FULL OUTER JOIN。