.net - SqlDataReader.ExecuteReader 没有异常，而 SQL Server 返回转换错误

Question

当我在 SQL Server Management Studio 中执行以下语句时

exec sp_executesql N'select 1 其中 1 = @p1',N'@p1 nvarchar(3)',@p1=N'a'

去

我收到以下错误

消息 245，第 16 级，状态 1，第 1 行

将 nvarchar 值“a”转换为数据类型 int 时转换失败。

但是当我使用 ExecuteReader 时，我没有得到任何异常

为什么？

如何在应用程序中将此错误作为异常获取和处理

导入 System.Data.SqlClient

模块模块1

Sub Main()

    Dim TestSqlConnection As SqlConnection = Nothing

    Dim TestSqlCommand As SqlCommand = Nothing

    Dim TestReader As SqlDataReader = Nothing

    Dim TestGetSchemaTable As DataTable = Nothing

    TestSqlConnection = New SqlConnection
    TestSqlConnection.ConnectionString = "Data Source=(local);Database=master;Integrated Security=true"
    TestSqlConnection.Open()
    TestSqlCommand = New SqlCommand()
    TestSqlCommand.Connection = TestSqlConnection
    TestSqlCommand.CommandType = CommandType.Text
    TestSqlCommand.CommandText = "select 1 where 1 = @p1"

    Dim TestSqlParameter As SqlParameter = New SqlParameter
    TestSqlParameter.ParameterName = "@p1"
    TestSqlParameter.SqlDbType = SqlDbType.NVarChar
    TestSqlParameter.Size = 3
    TestSqlParameter.Direction = ParameterDirection.Input
    TestSqlParameter.Value = "a"
    TestSqlCommand.Parameters.Add(TestSqlParameter)

    Try
        TestReader = TestSqlCommand.ExecuteReader()
    Catch ex As Exception
        Console.WriteLine("Exception")
    Finally
        Console.WriteLine("Finally")
    End Try
End Sub

端模块

Answer 1

ExecuteReader 实际上并不执行查询。第一次调用 .Read() 会抛出错误。

如果你只想捕获 SqlException您可以执行以下操作:

Try
    TestReader = TestSqlCommand.ExecuteReader()
    TestReader.Read()
Catch ex As SqlException
    Console.WriteLine("SQL error.")
Catch ex As Exception
    Console.WriteLine("Exception")
Finally
    Console.WriteLine("Finally")
End Try