来自.NET的参数化查询的SQLServerCE问题

我想弄清楚这件事，真是让人毛骨悚然

当我使用参数时，我不能使参数化查询在VB.Net中工作

根据我所发现的，在函数中使用参数From.NET会引发一个错误（请参见示例代码）。但是，在VisualStudio的“查询”窗口中运行“不工作”查询可以正常工作

引发的错误是：

25922-函数的参数无效

信息来源：

示例代码：

Imports System.Data.SqlServerCe

Public Class MiniDemo

    Public Shared Sub Main()
        Dim cs As String = "Data Source=Inventory.sdf; Persist Security Info=False;"
        Dim db As New SqlCeConnection(cs)
        db.Open()


        ''#Using parameters works
        Dim cmd As SqlCeCommand = db.CreateCommand()

        cmd.CommandText = "INSERT INTO inventory_type (inv_type_id, inv_type_name) VALUES (@id, @name)"
        cmd.Parameters.Add("@id", 1)
        cmd.Parameters.Add("@name", "test")
        cmd.ExecuteNonQuery()



        ''#Using parameters in functions does not work
        Dim cmd2 As SqlCeCommand = db.CreateCommand()

            ''#Broken on multiple lines for readability (built using string builders in real code)
        cmd2.CommandText = 
                     "SELECT 
                        inv_type_id, 
                        inv_type_name 
                      FROM
                        inventory_type 
                      WHERE 
                        ((@id IS NULL) OR (inv_type_id = @id)) AND 
                        ((@name IS NULL) OR (inv_type_name = @name))"

        cmd2.Parameters.Add("@id", 1)
        cmd2.Parameters.Add("@name", "test") ''# Would not work with DBNull.Value either

        Dim da2 As New SqlCeDataAdapter(cmd2)
        Dim dt2 As New DataTable()
        da2.Fill(dt2)
        db.Close()
    End Sub

End Class

    Dim cmd As SqlCeCommand = db.CreateCommand()

    cmd.CommandText = "SELECT COALESCE(@param1, @param2);"
    cmd.Parameters.Add("@param1", 1)
    cmd.Parameters.Add("@param2", "test")
    cmd.ExecuteScalar()

---

最后，我找到了解决这个问题的办法

如果未设置参数的DBType属性，则在函数中使用参数会崩溃：

这将崩溃：

Imports System.Data.SqlServerCe

Public Class MiniDemo

    Public Shared Sub Main()
        Dim cs As String = "Data Source=Inventory.sdf; Persist Security Info=False;"
        Dim db As New SqlCeConnection(cs)
        db.Open()


        ''#Using parameters works
        Dim cmd As SqlCeCommand = db.CreateCommand()

        cmd.CommandText = "INSERT INTO inventory_type (inv_type_id, inv_type_name) VALUES (@id, @name)"
        cmd.Parameters.Add("@id", 1)
        cmd.Parameters.Add("@name", "test")
        cmd.ExecuteNonQuery()



        ''#Using parameters in functions does not work
        Dim cmd2 As SqlCeCommand = db.CreateCommand()

            ''#Broken on multiple lines for readability (built using string builders in real code)
        cmd2.CommandText = 
                     "SELECT 
                        inv_type_id, 
                        inv_type_name 
                      FROM
                        inventory_type 
                      WHERE 
                        ((@id IS NULL) OR (inv_type_id = @id)) AND 
                        ((@name IS NULL) OR (inv_type_name = @name))"

        cmd2.Parameters.Add("@id", 1)
        cmd2.Parameters.Add("@name", "test") ''# Would not work with DBNull.Value either

        Dim da2 As New SqlCeDataAdapter(cmd2)
        Dim dt2 As New DataTable()
        da2.Fill(dt2)
        db.Close()
    End Sub

End Class

    Dim cmd As SqlCeCommand = db.CreateCommand()

    cmd.CommandText = "SELECT COALESCE(@param1, @param2);"
    cmd.Parameters.Add("@param1", 1)
    cmd.Parameters.Add("@param2", "test")
    cmd.ExecuteScalar()

如果设置了参数的DBType属性，则在函数中使用参数将起作用

这将起作用：

    Dim cmd As SqlCeCommand = db.CreateCommand()

    cmd.CommandText = "SELECT COALESCE(@param1, @param2);"
    cmd.Parameters.Add("@param1", 1).DbType = DbType.Int32
    cmd.Parameters.Add("@param2", "test").DbType = DbType.String
    cmd.ExecuteScalar()

---

我看不出你们的第一个和第二个样品之间有实质性的区别。你指的是什么“功能”。Fill（）？生产代码中是否存在@nom和@nome差异？或者就在这个例子中？就在这个例子中，corrected@Joel：2之间的区别是，第二个失败是因为is NULL（它在幕后转换为ISNULL（@id），COALESCE（@id，0）=0）将产生相同的错误。您是否尝试过

inv\u type\u name=COALESCE（@name，inv\u type\u name）

（参数值为DBNull.Value）？