C# 如何让我的LINQ查询生成我期望的SQL语句？

我有一个简单的网页表单，其中有3个文本框和一个带有搜索按钮的下拉列表

这是我根据从4个控件中选择的输入筛选EF4.0上下文的代码：

string mFormId = ddlTransValueSearchFormId.SelectedItem.Text.ToString().Trim();
string mControlId = ddlTransValueSearchControlId.SelectedItem.Text.ToString().Trim();
int mTransCategoryId;
try
{
    mTransCategoryId = Int32.Parse(ddlTransValueSearchCategoryId.SelectedItem.Value.ToString());
}
catch(Exception ex)
{
    throw ex;
}
string mDefaultTransValue = tbTransValueSearchDefaultValue.Text.ToString().Trim();

我的LINQ查询

生成的SQL语句

使用探查器，这是生成的SQL查询：

declare @p__linq__0 nvarchar(4000),@p__linq__1 nvarchar(4000),@p__linq__2 nvarchar(4000),@p__linq__3 nvarchar(4000),@p__linq__4 int,@p__linq__5 int,@p__linq__6 nvarchar(4000),@p__linq__7 nvarchar(4000)
SELECT @p__linq__0=N'',@p__linq__1=N'%%',@p__linq__2=N'',@p__linq__3=N'%%',@p__linq__4=1,@p__linq__5=1,@p__linq__6=N'cat',@p__linq__7=N'%cat%'

SELECT 
[Extent1].[TRAN_VALUE_ID] AS [TRAN_VALUE_ID], 
[Extent1].[FORM_ID] AS [FORM_ID], 
[Extent1].[CONTROL_ID] AS [CONTROL_ID], 
[Extent1].[TRANS_CATEGORY_ID] AS [TRANS_CATEGORY_ID], 
[Extent2].[CATEGORY_NAME] AS [CATEGORY_NAME], 
[Extent1].[DEFAULT_TRAN_VALUE] AS [DEFAULT_TRAN_VALUE]
FROM  [dbo].[TRANS_VALUES] AS [Extent1]
LEFT OUTER JOIN [dbo].[TRANS_CATEGORY] AS [Extent2] ON [Extent1].[TRANS_CATEGORY_ID] = [Extent2].[TRANS_CATEGORY_ID]
WHERE 
(CASE 
    WHEN (N'' = @p__linq__0) THEN cast(1 as bit) 
    WHEN (([Extent1].[FORM_ID] LIKE @p__linq__1 ESCAPE N'~') AND (N'' = @p__linq__2)) THEN cast(1 as bit) 
    WHEN (([Extent1].[CONTROL_ID] LIKE @p__linq__3 ESCAPE N'~') AND (-1 = @p__linq__4)) THEN cast(1 as bit) 
    WHEN (([Extent1].[TRANS_CATEGORY_ID] = @p__linq__5) AND (N'' = @p__linq__6)) THEN cast(1 as bit) 
    WHEN ([Extent1].[DEFAULT_TRAN_VALUE] LIKE @p__linq__7 ESCAPE N'~') THEN cast(1 as bit) 
    WHEN ( NOT ([Extent1].[DEFAULT_TRAN_VALUE] LIKE @p__linq__7 ESCAPE N'~')) THEN cast(0 as bit) 
END) = 1

这不是我想要的。无论参数值如何，EF生成脚本的方式都是从数据库返回所有行

这里出了什么问题

我想要的SQL语句

实际上，在SQL Server方面，我需要和考虑的是优化EF来生成这种查询。

SELECT 
[Extent1].[TRAN_VALUE_ID] AS [TRAN_VALUE_ID], 
[Extent1].[FORM_ID] AS [FORM_ID], 
[Extent1].[CONTROL_ID] AS [CONTROL_ID], 
[Extent1].[TRANS_CATEGORY_ID] AS [TRANS_CATEGORY_ID], 
[Extent2].[CATEGORY_NAME] AS [CATEGORY_NAME], 
[Extent1].[DEFAULT_TRAN_VALUE] AS [DEFAULT_TRAN_VALUE]
FROM  [dbo].[TRANS_VALUES] AS [Extent1]
LEFT OUTER JOIN [dbo].[TRANS_CATEGORY] AS [Extent2] ON [Extent1].[TRANS_CATEGORY_ID] = [Extent2].[TRANS_CATEGORY_ID]
WHERE
    ISNULL([Extent1].[FORM_ID],N'') LIKE '%' + COALESCE(@p__linq__0,[Extent1].[FORM_ID],N'') + '%'
AND ISNULL([Extent1].[CONTROL_ID],N'') LIKE '%' + COALESCE(@p__linq__1,[Extent1].[CONTROL_ID],N'') + '%'    
AND ISNULL([Extent1].[TRANS_CATEGORY_ID],-1) = COALESCE(@p__linq__2,[Extent1].[TRANS_CATEGORY_ID],-1)
AND ISNULL([Extent1].[DEFAULT_TRAN_VALUE],N'') LIKE '%' + COALESCE(@p__linq__3,[Extent1].[DEFAULT_TRAN_VALUE],N'') + '%'    
go

---

试着这样写：

(from defaultValue in efSchema.TRANS_VALUES
 .Include("TRANS_CATEGORY")
 where (defaultValue.FormId.Contains(mFormId) || mFormId == "")
     && (defaultValue.ControlId.Contains(mControlId) || mControlId == "")
     && (defaultValue.TransCategoryId.Contains(mTransCategoryId) || mTransCategoryId == "")
     && (defaultValue.DefaultTranValue.Contains(mDefaultTransValue) || mDefaultTransValue == ""))

---

如果您以小步骤构造查询，这将简单得多

var query = efSchema.TRANS_VALUES.Include("TRANS_CATEGORY");
if(!string.IsNullOrEmpty(mFormId))
{
    query = query.Where(defaultValue => defaultValue.FormId.Contains(mFormId));
}
if(!string.IsNullOrEmpty(mControlId))
{
    query = query.Where(defaultValue => defaultValue.ControlId.Contains(mControlId));
}
if(mTransCategoryId != -1)
{
    query = query.Where(defaultValue => defaultValue.TransCategoryId == mTransCategoryId);
}
if(!string.IsNullOrEmpty(mDefaultTransValue))
{
    query = query.Where(defaultValue => defaultValue.DefaultTransValue.Contains(mDefaultTransValue));
}

gvTransValues.DataSource = query.Select(defaultValue => new 
                        { 
                            TranValueId = defaultValue.TranValueId,
                            FormId = defaultValue.FormId,
                            ControlId = defaultValue.ControlId,
                            TransCategoryId = defaultValue.TransCategoryId,
                            CategoryName = defaultValue.TRANS_CATEGORY.CategoryName,
                            DefaultTranValue = defaultValue.DefaultTranValue,
                        });

---

我认为它应该是这样工作的，但是您可能必须将查询的初始类型指定给IQueryable

，这看起来是个问题。尝试在条件周围加上括号。如果EF不能自动生成所需的代码，我建议您将其包装在存储过程中。@Johnbot-您是对的！我在where子句周围添加了偏执，现在它可以正常工作了。谢谢你，伙计！这样做了，现在就可以了！谢谢虽然你的情况与我需要的不一样，但我需要考虑将此标记为已回答，以便你的问题从未回答的队列中删除。谢谢，祝你好运！

var query = efSchema.TRANS_VALUES.Include("TRANS_CATEGORY");
if(!string.IsNullOrEmpty(mFormId))
{
    query = query.Where(defaultValue => defaultValue.FormId.Contains(mFormId));
}
if(!string.IsNullOrEmpty(mControlId))
{
    query = query.Where(defaultValue => defaultValue.ControlId.Contains(mControlId));
}
if(mTransCategoryId != -1)
{
    query = query.Where(defaultValue => defaultValue.TransCategoryId == mTransCategoryId);
}
if(!string.IsNullOrEmpty(mDefaultTransValue))
{
    query = query.Where(defaultValue => defaultValue.DefaultTransValue.Contains(mDefaultTransValue));
}

gvTransValues.DataSource = query.Select(defaultValue => new 
                        { 
                            TranValueId = defaultValue.TranValueId,
                            FormId = defaultValue.FormId,
                            ControlId = defaultValue.ControlId,
                            TransCategoryId = defaultValue.TransCategoryId,
                            CategoryName = defaultValue.TRANS_CATEGORY.CategoryName,
                            DefaultTranValue = defaultValue.DefaultTranValue,
                        });