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数据库兼容,在开发项目过程中,难免会遇到 更改数据库,或者后期 项目升级,也可能会遇到这种情况,这里就说明下oralce和db2兼容开发注意事项。

兼容oralce、db2开发注意事项(前提是db2版本是9.7,且是开启PLSQL编译选项之后创建的数据库):

 1. 在like 之后若使用了表字段,应统一改成使用locate函数

   如:   oralce写法:    select * from fw_right a where '03' like a.rightid||'%';   兼容写法:    select * from fw_right a where locate('03',a.rightid) = 1;   oralce写法:    select * from fw_right a where '03' like '%'||a.rightid||'%';   兼容写法:    select * from fw_right a where locate('03',a.rightid) > 0;

 2. 视图中使用的别名不应该与当前表字段同名

    如以下语句,在Oracle中不会有问题,但在db2中会报"SQL0153N"错误:

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 e.g:  CREATE OR REPLACE VIEW V_WF_TODOLIST AS     select c.process_def_id, c.process_def_name, a.action_def_id,       a.work_item_id,  a.bae007,      a.action_def_name,       a.state,     a.pre_wi_id,    a.work_type,       a.operid,     a.x_oprator_ids,  b.process_key_info,       to_char(to_date(a.start_time,  'yyyymmddhh24miss'),'yyyy-mm-dd hh24:mi:ss') as start_time,       to_char(to_date(a.complete_time,'yyyymmddhh24miss'),'yyyy-mm-dd hh24:mi:ss') as complete_time,       a.filter_opr, a.memo,a.bae002,a.bae003, a.bae006,c.x_action_def_ids from wf_work_item a, wf_process_instance b, wf_action_def c  where a.action_def_id = c.action_def_id  and b.process_def_id = c.process_def_id  and a.bae007 = b.bae007  and a.state in('0','2')

        兼容写法:

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 CREATE OR REPLACE VIEW V_WF_TODOLIST AS   select c.process_def_id, c.process_def_name, a.action_def_id,    a.work_item_id,  a.bae007,      a.action_def_name,    a.state,     a.pre_wi_id,    a.work_type,    a.operid,     a.x_oprator_ids,  b.process_key_info,    to_char(to_date(a.start_time,  'yyyymmddhh24miss'),'yyyy-mm-dd hh24:mi:ss') as start_time_0,    to_char(to_date(a.complete_time,'yyyymmddhh24miss'),'yyyy-mm-dd hh24:mi:ss') as complete_time_0,    a.filter_opr, a.memo,a.bae002,a.bae003, a.bae006,c.x_action_def_ids    from wf_work_item a, wf_process_instance b, wf_action_def c    where a.action_def_id = c.action_def_id    and b.process_def_id = c.process_def_id    and a.bae007 = b.bae007    and a.state in('0','2')   

   3.在下列情况下不允许 ORDER BY 或 FETCH FIRST n ROWS ONLY: 

*  外层全查询视图   *  "SQL 表函数"的 RETURN 语句中的外层全查询   *  具体化查询表定义   *  未用圆括号括起来的子查询

  否则会报"SQL20211N  规范 ORDER BY 或 FETCH FIRST n ROWS ONLY 无效。"错误.  

  e.g:   oralce写法:

? 1 2 3 4 5 6 7 8 9 10 CREATE OR REPLACE VIEW V_FW_BLANK_BULLETIN as select id,   bae001, operunitid, operunittype, unitsubtype, ifergency,   title, content, digest,  duetime,   validto,   aae100,   bae006, bae002, bae003,  id as colid,   substr(digest,1,20) as digest2  from fw_bulletin where duetime <= to_char(sysdate,'yyyymmddhh24miss')  and (to_char(validto) >= to_char(sysdate,'yyyymmddhh24miss') or validto is null)  and aae100 ='1' order by ifergency desc, id desc, duetime desc

      兼容写法:

? 1 2 3 4 5 6 7 8 9 10 11 12 CREATE OR REPLACE VIEW V_FW_BLANK_BULLETIN as select * from (select id,   bae001, operunitid, operunittype, unitsubtype, ifergency,  title, content, digest,  duetime,   validto,   aae100,  bae006, bae002, bae003,  id as colid,  substr(digest,1,20) as digest2 from fw_bulletin where duetime <= to_char(sysdate,'yyyymmddhh24miss') and (to_char(validto) >= to_char(sysdate,'yyyymmddhh24miss') or validto is null) and aae100 ='1' order by ifergency desc, id desc, duetime desc)

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