c# - SQL 查询在 SQL Server 2008 中有效，但在 C# 中无效

Question

我正在开发一个应用程序，我必须从数据库中检索一些数据。我正在使用以下查询。

SELECT DISTINCT Context.ContextId, ContextName 
FROM Context
INNER JOIN RunInstance 
   ON Context.ContextId IN 
      (SELECT RunInstance.ContextId 
       FROM RunInstance 
       INNER JOIN ProcessInstance 
          ON RunInstance.RunInstanceId 
             IN (SELECT RunInstanceId FROM ProcessInstance 
                 WHERE RiskDate = '2010-08-20' )); 

此查询在 SQL Server 2008 中完美运行。

但是，当我将它放在我的 C# 应用程序中时，它没有显示任何输出。

我的代码：

string squery = @"SELECT DISTINCT Context.ContextId, ContextName FROM Context INNER JOIN RunInstance ON Context.ContextId IN 
    (Select RunInstance.ContextId From RunInstance 
    INNER JOIN ProcessInstance ON RunInstance.RunInstanceId 
    IN (SELECT RunInstanceId FROM ProcessInstance Where 
    RiskDate = '2010-08-20' )); ";

using(SqlConnection sqcon = new SqlConnection("Data Source=WMLON-Z8-SQL20,61433;Initial Catalog=statusdb;Integrated Security=True")){
    sqcon.Open();
    using(SqlCommand command = new SqlCommand(squery,sqcon))
        using(SqlDataReader reader = command.ExecuteReader()){
            while(reader.Read()){
                Console.WriteLine(reader[0]+"\t"+reader[1]);
            }
        }
}     

谁能告诉我问题是什么？

Answer 1

请把CommandText放到CommandType中试试。

using(SqlConnection sqcon = new SqlConnection(
"Data Source=WMLON-Z8-SQL20,61433;Initial Catalog=statusdb;Integrated Security=True"))
{
   using(SqlCommand command = new SqlCommand(squery,sqcon)){
      command.CommandType = CommandType.Text;
      sqcon.Open();
      using(SqlDataReader reader = command.ExecuteReader())
      {
          while(reader.Read()){
            Console.WriteLine(reader[0]+"\t"+reader[1]);
          }
      }
      sqcon.Close();
   }
} 

-- Using EXISTS or IN could improve your query
    SELECT DISTINCT
            Context.ContextId ,
            ContextName
    FROM    Context
            INNER JOIN RunInstance ON Context.ContextId = RunInstance.ContextId 
            INNER JOIN ProcessInstance ON RunInstance.RunInstanceId = ProcessInstance.RunInstanceId
    WHERE   RiskDate = '2010-08-20'