Linq to Entity 多条件 OR查询

技术背景：框架MVC，linq to Entity 需要一定的lambda书写能力

问题：在简单的orm中完成一些简单的增删查改是通过where insert delete update 完成的，但是在这个过程中出现了一个需求：多项条件的and 和or 的组合查询

众所周知直接通过linq 写的话很方便，但是我们的框架使用了linq to entity,如果只用lambda来写比较复杂的and 和or 查询就比较麻烦了。

一：简单and 和or 查询

public void TextFoZK()
        {
            using (var dbContext = new CRMDbContext())
            {
                //第一句解析出来的sql是  select * from membertype where commercialtenantid=0 or name='住客'
                dbContext.MemberType.Where(m => m.CommercialTenantID == 0 || m.Name == "住客");
                //第二句解析出来的sql是  select * from membertype where commercialtenantid=0 and name='住客'
                dbContext.MemberType.Where(m => m.CommercialTenantID == 0 && m.Name == "住客");
            }
        }

二：复杂逻辑的and 和or 查询

public void TextFoZK(int status, string name, int commercialtenantid)
        {
            using (var dbContext = new CRMDbContext())
            {
                IQueryable<MemberType> iqm = dbContext.MemberType;
                if (status > 0)
                {
                    iqm = iqm.Where(m => m.Status == status);
                }
                if (!string.IsNullOrEmpty(name))
                {
                    iqm = iqm.Where(m => m.Name == name && m.CommercialTenantID == commercialtenantid);
                }
                iqm = iqm.Where(m => m.ID > 0 || m.ID == 1);
                iqm.ToList();
                //select * from membertype where (status=1) and (name='住客' and commercialtenantid=1) and (id>0 or id=1)
            }
        }

这里使用了IQuerable的扩展方法where ,代表着每个iquerable之间为and 关系，但是又可以包含or 

三：复杂and 和 or

public void TextFoZK(int status, string name, int commercialtenantid)
        {
            using (var dbContext = new CRMDbContext())
            {
                IQueryable<MemberType> iqm = dbContext.MemberType;
                if (status > 0)
                {
                    iqm = iqm.Where(m => m.Status == status);
                }
                if (!string.IsNullOrEmpty(name))
                {
                    iqm = iqm.Where(m => m.Name == name && m.CommercialTenantID == commercialtenantid);
                }
                //重新声明一个iq，两个iq 之间为or 关系
                IQueryable<MemberType> iqmtwo = dbContext.MemberType;
                iqmtwo = iqmtwo.Where(m => m.ID > 0 || m.ID == 1);
                iqm = iqm.Union(iqmtwo);
                iqm.ToList();
                
            }
        }

这里使用了iquerable中的扩展方法union 可以把多个iq方法合成为一个iq ,之间为union all  关系

第一个iq 为一个结果集，第二个为一个结果集，最后合并两个结果集。

可以满足一个sql过程中查询多处结果的要求，但是生成的sql还是有点麻烦

 1 exec sp_executesql N'SELECT TOP (10) 
 2 [Project4].[C1] AS [C1], 
 3 [Project4].[C2] AS [C2], 
 4 [Project4].[C3] AS [C3], 
 5 [Project4].[C4] AS [C4], 
 6 [Project4].[C5] AS [C5], 
 7 [Project4].[C6] AS [C6], 
 8 [Project4].[C7] AS [C7], 
 9 [Project4].[C8] AS [C8], 
10 [Project4].[C9] AS [C9], 
11 [Project4].[C10] AS [C10]
12 FROM ( SELECT [Project4].[C1] AS [C1], [Project4].[C2] AS [C2], [Project4].[C3] AS [C3], [Project4].[C4] AS [C4], [Project4].[C5] AS [C5], [Project4].[C6] AS [C6], [Project4].[C7] AS [C7], [Project4].[C8] AS [C8], [Project4].[C9] AS [C9], [Project4].[C10] AS [C10], row_number() OVER (ORDER BY [Project4].[C1] ASC) AS [row_number]
13     FROM ( SELECT 
14         [Distinct1].[C1] AS [C1], 
15         [Distinct1].[C2] AS [C2], 
16         [Distinct1].[C3] AS [C3], 
17         [Distinct1].[C4] AS [C4], 
18         [Distinct1].[C5] AS [C5], 
19         [Distinct1].[C6] AS [C6], 
20         [Distinct1].[C7] AS [C7], 
21         [Distinct1].[C8] AS [C8], 
22         [Distinct1].[C9] AS [C9], 
23         [Distinct1].[C10] AS [C10]
24         FROM ( SELECT DISTINCT 
25             [UnionAll1].[ID] AS [C1], 
26             [UnionAll1].[CommercialTenantID] AS [C2], 
27             [UnionAll1].[Name] AS [C3], 
28             [UnionAll1].[Status] AS [C4], 
29             [UnionAll1].[Discount] AS [C5], 
30             [UnionAll1].[GiveIntegralScale] AS [C6], 
31             [UnionAll1].[Creator] AS [C7], 
32             [UnionAll1].[CreatorID] AS [C8], 
33             [UnionAll1].[GMT_Create] AS [C9], 
34             [UnionAll1].[GMT_Modified] AS [C10]
35             FROM  (SELECT 
36                 [Extent1].[ID] AS [ID], 
37                 [Extent1].[CommercialTenantID] AS [CommercialTenantID], 
38                 [Extent1].[Name] AS [Name], 
39                 [Extent1].[Status] AS [Status], 
40                 [Extent1].[Discount] AS [Discount], 
41                 [Extent1].[GiveIntegralScale] AS [GiveIntegralScale], 
42                 [Extent1].[Creator] AS [Creator], 
43                 [Extent1].[CreatorID] AS [CreatorID], 
44                 [Extent1].[GMT_Create] AS [GMT_Create], 
45                 [Extent1].[GMT_Modified] AS [GMT_Modified]
46                 FROM [dbo].[commercialtenant_membertype] AS [Extent1]
47                 WHERE [Extent1].[CommercialTenantID] = @p__linq__0
48             UNION ALL
49                 SELECT 
50                 [Extent2].[ID] AS [ID], 
51                 [Extent2].[CommercialTenantID] AS [CommercialTenantID], 
52                 [Extent2].[Name] AS [Name], 
53                 [Extent2].[Status] AS [Status], 
54                 [Extent2].[Discount] AS [Discount], 
55                 [Extent2].[GiveIntegralScale] AS [GiveIntegralScale], 
56                 [Extent2].[Creator] AS [Creator], 
57                 [Extent2].[CreatorID] AS [CreatorID], 
58                 [Extent2].[GMT_Create] AS [GMT_Create], 
59                 [Extent2].[GMT_Modified] AS [GMT_Modified]
60                 FROM [dbo].[commercialtenant_membertype] AS [Extent2]
61                 WHERE (0 = [Extent2].[CommercialTenantID]) AND (N''住客'' = [Extent2].[Name])) AS [UnionAll1]
62         )  AS [Distinct1]
63     )  AS [Project4]
64 )  AS [Project4]
65 WHERE [Project4].[row_number] > 0
66 ORDER BY [Project4].[C1] ASC',N'@p__linq__0 int',@p__linq__0=1

sql 想看的可以打开看看