Entity Framework 4.0新增对T-SQL的支持

Entity Framework 4.0新增对T-SQL的支持2011-11-17 博客园张磊EF4.0中新增了ExecuteStoreQuery,ExecuteStoreCommand,ExecuteFunction等方法,完美支持T- SQL

之前在EF中用Linq进行left join查询和报表数据查询简直是一场噩梦,以下代码就是例子:

Linq左连接查询N张表示例代码

1 public List<Info> getMapUnitList（int MapId）
2     {
3        var var1 = from mu in epm.MapUnit
4            join us in  epm.UnitStatus
5            on mu.Unit equals us.Unit into  _UnitStatus
6            join cu in epm.ContractUnit
7             on mu.Unit equals cu.Unit into _ContractUnit
8            where  mu.Map.MapId == MapId
9            select new Info（）
10             {
11              map = mu.Map
12               ,
13              mapstatus = null
14               ,
15              mapunit = mu
16              ,
17               unit = mu.Unit
18              ,
19               status = _UnitStatus.Select（a => a.Status）.FirstOrDefault（） 
20              ,
21              contract =  _ContractUnit.Select（a => a.Contract）.FirstOrDefault（）
22               ,
23              customer = null
24               ,
25              boothtype = null
26             };
27       var var2 = from v1 in var1
28            join  ms in epm.MapStatus
29             on new { map = v1.map, status =  v1.status }
30             equals new { map = ms.Map, status =  ms.Status } into _MapStatus
31            select new Info（）
32             {
33              map = null
34               ,
35              mapstatus = _MapStatus.FirstOrDefault（）
36               ,
37              mapunit = v1.mapunit
38               ,
39              unit = v1.unit
40               ,
41              status = v1.status
42               ,
43              contract = v1.contract
44               ,
45              customer = null
46               ,
47              boothtype = null
48             };
49       var var3 = from v2 in var2
50             from ubtl in epm.UnitBoothType
51            where ubtl.Unit.UnitId ==  v2.unit.UnitId
52            join cc in epm.CustomerContract
53             on v2.contract equals cc.Contract into _CustomerContract
54             select new Info（）
55            {
56               map = null
57              ,
58               mapstatus = v2.mapstatus
59              ,
60               mapunit = v2.mapunit
61              ,
62               unit = v2.unit
63              ,
64               status = v2.status
65              ,
66               contract = v2.contract
67              ,
68               customer = _CustomerContract.Select（a => a.Customer）.FirstOrDefault（）
69               ,
70              boothtype = ubtl.BoothType
71             };
72       List<Info> infos = var3.ToList（）;
73        return infos;
74     }