EntityFramework查询oracle数据库时报ora-12704: character set mismatch

1、这段linq,执行期间报ora-12704:character set mismatch错误。

1 var query = from m in ctx.MENU
2     where (m.SUPER_MENU_ID ?? "") == (parentMenuId ?? "")
3     orderby m.SORT_ID descending
4     select new { m.SORT_ID };

生成出来的sql如下:

 1 SELECT "Project1"."SORT_ID" AS "SORT_ID"
 2    FROM (
 3 
 4 SELECT "Extent1"."SORT_ID" AS "SORT_ID"
 5    FROM "BA"."MENU" "Extent1"
 6  WHERE ((CASE WHEN("Extent1"."SUPER_MENU_ID" IS NULL) THEN ‘‘ 
 7                     ELSE "Extent1"."SUPER_MENU_ID" END) =
 8         (CASE WHEN(&p__linq__0 IS NULL) THEN ‘‘ 
 9                     ELSE &p__linq__0 END))
10 
11 ) "Project1"
12 ORDER BY "Project1"."SORT_ID" DESC

但是这条sql单独放到plsql里跑是OK的。

 

2、改成这样,让生成的sql去掉了里面的case when就OK了。

1 parentMenuId = parentMenuId ?? "";
2 var query = from m in ctx.MENU
3       where m.SUPER_MENU_ID == parentMenuId
4     orderby m.SORT_ID descending
5       select new { m.SORT_ID };

生成的sql如下:

1 SELECT "Project1"."SORT_ID" AS "SORT_ID" FROM ( 
2 
3 SELECT "Extent1"."SORT_ID" AS "SORT_ID"
4    FROM "BA"."MENU" "Extent1"
5 WHERE ("Extent1"."SUPER_MENU_ID" = :p__linq__0)
6 
7 ) "Project1"
8 ORDER BY "Project1"."SORT_ID" DESC

 

3、目前的猜测是,ef生成出来的case when有问题,调整linq不生成case when即可。但奇怪的是,同样的sql在plsql里跑居然也是ok的,手工修改客户端的字符集也无法在plsql里重现这个问题,如下:

修改注册表里,HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\KEY_OraClient11g_home2\NLS_LANG,在plsql里客户端使用不同于服务端的字符集,但无法生成同样的错误。

修改前:

NLS_LANG = SIMPLIFIED CHINESE_CHINA.ZHS16GBK
Character Sets
Character size: 2 byte(s)
CharSetID: 852
NCharSetID: 2000
Unicode Support: True
NLS_LANG: SIMPLIFIED CHINESE_CHINA.ZHS16GBK
NLS_CHARACTERSET: ZHS16GBK
NLS_NCHAR_CHARACTERSET: AL16UTF16

修改后:

NLS_LANG = SIMPLIFIED CHINESE_CHINA.AL32UTF8
Character Sets
Character size: 2 byte(s)
CharSetID: 873
NCharSetID: 2000
Unicode Support: True
NLS_LANG: SIMPLIFIED CHINESE_CHINA.AL32UTF8
NLS_CHARACTERSET: ZHS16GBK
NLS_NCHAR_CHARACTERSET: AL16UTF16

 

4、这个问题只是暂时解决,仍然存疑中,待完善。主要参考这篇:

ef4 part 8: database agnostic linq to entities

EntityFramework查询oracle数据库时报ora-12704: character set mismatch,古老的榕树,5-wow.com

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