返回int而不是数据表

Question

如何更改下面的语法以返回Int而不是数据表。我不需要一个datatable它只是一个值，将在查询中返回。这是整个数据访问的新事物。谢谢你的帮助。的

public DataTable GetMemberID(string guid) 
    { 
     string strConectionString = ConfigurationManager.AppSettings["DataBaseConnection"]; 

     //set up sql 
     string StrSql = "SELECT MemberID FROM MEMBERS WHERE (Guid = @GuidID)"; 

     DataTable dt = new DataTable(); 
     using (SqlDataAdapter daObj = new SqlDataAdapter(StrSql, strConectionString)) 
     { 
      daObj.SelectCommand.Parameters.Add("@GuidID", SqlDbType.Int); 
      daObj.SelectCommand.Parameters["@GuidID"].Value = guid; 
      //fill data table 
      daObj.Fill(dt); 
     } 
     return dt; 

    } 

Answer 1

public int GetMemberID(string guid) 
    { 
     string strConectionString = ConfigurationManager.AppSettings["DataBaseConnection"]; 

     //set up sql 
     string StrSql = "SELECT MemberID FROM MEMBERS WHERE (Guid = @GuidID)"; 

     DataTable dt = new DataTable(); 
     using (SqlDataAdapter daObj = new SqlDataAdapter(StrSql, strConectionString)) 
     { 
      daObj.SelectCommand.Parameters.Add("@GuidID", SqlDbType.Int); 
      daObj.SelectCommand.Parameters["@GuidID"].Value = guid; 
      //fill data table 
      daObj.Fill(dt); 
     } 
     return Convert.ToInt32(dt["MemberID"][0]); 

    } 

Answer 2

代替：

return dt; 

使用本：

if (dt.rows.count > 0) 
    return (int)dt.rows[0][0]; 

宣言还需要改为：

public int GetMemberID(string guid) 

Answer 3

使用SqlCommand和ExecuteScalar，而不是填充DataTable：

string StrSql = "SELECT MemberID FROM MEMBERS WHERE (Guid = @GuidID)"; 
using(var cmd = new SqlCommand(sql, connection)) 
{ 
    cmd.Parameters.Add("@GuidID", SqlDbType.Int).Value = guid; 
    return (int)cmd.ExecuteScalar(); 
} 

Answer 4

可以使用SqlCommand代替SqlDataAdapter：

int memberId = 0; 
using (var connection = new SqlConnection(conectionString)) 
using (var command = new SqlCommand(StrSql, connection)) 
{ 
    command.Parameters.Add("@GuidID", SqlDbType.Int).Value = guid; 
    memberId = (int) command.ExecuteScalar(); 
} 

return memberId;