如何重写oracle SQL语句以符合ansi-98并转换为DB2格式

Question

如何将这个旧的 oracle SQL 语句转换为 DB2 ANSI 98 编译：

SELECT 
    O.OBJECT_NAME AS OBJECT_NAME,
    ATT.ATTRIBUTE_NAME AS ATTRIBUTE_NAME, 

    (CASE WHEN R.RULE_NAME = 'LAST_UPDATE' THEN 1 
          WHEN R.RULE_NAME = 'SOURCE_SUPREMACY' THEN 2 
          ELSE 3 END) 

    ID_RULE, 
    RD.SRC_CODE, 
    RD.WEIGTH 
FROM 
    XOBJRULE ORL, 
    XOBJECT O, 
    XATTRIBUTE ATT, 
    XRULE R, 
    XOBJRULEDET RD, 
    CDSOURCEIDENTTP S   
WHERE 
    ORL.ID_OBJECT = O.ID_OBJECT(+) AND 
    ORL.ID_ATTRIBUTE = ATT.ID_ATTRIBUTE(+) AND 
    ORL.ID_RULE = R.ID_RULE AND 
    R.ID_RULE = RD.ID_RULE(+) AND 
    RD.SRC_CODE = S.SOURCE_IDENT_TP_CD(+) AND 
    ORL.PERSON_ORGANIZATION IN (1,3) 
ORDER BY 1,2,5 ASC

此 SQL 语句是从 Java 调试中提取的。我怎么能把它转换成 DB2 格式而不显着改变符号，这样我就不需要检查 Java 代码逻辑了？

Answer 1

查询使用 Oracle 自己的外连接语法(+)。对于 DB2，您需要将所有连接转换为 ANSI SQL 92 显式连接语法：LEFT OUTER JOIN。

...
FROM 
    XOBJRULE ORL
    left outer join XOBJECT O on ORL.ID_OBJECT = O.ID_OBJECT
    left outer join XATTRIBUTE ATT on ORL.ID_ATTRIBUTE = ATT.ID_ATTRIBUTE 
    inner join XRULE R on ORL.ID_RULE = R.ID_RULE 
    left outer join XOBJRULEDET RD on R.ID_RULE = RD.ID_RULE 
    left outer join CDSOURCEIDENTTP S on RD.SRC_CODE = S.SOURCE_IDENT_TP_CD 
WHERE ORL.PERSON_ORGANIZATION IN (1,3)