如何利用ASP.NET实现返回数据库查询结果的条数？

在ASP.NET中返回查询条数，可以使用数据库操作语句如SELECT COUNT(*)。

一、使用SQL语句查询数据条数

1、直接查询总条数：通过执行SELECT COUNT(*) FROM table_name;语句，可以获取指定表中的总记录数，要查询名为users的表中的用户总数，可以使用以下代码：

**C#代码示例

      string strSQL = "SELECT COUNT(*) FROM users";
      SqlCommand comm = new SqlCommand(strSQL, conn);
      int count = Convert.ToInt32(comm.ExecuteScalar());
      Response.Write("Total Records: " + count);

VB代码示例

      Dim conn, rs, sql
      Set conn = Server.CreateObject("ADODB.Connection")
      conn.Open "Provider=SQLOLEDB; Data Source=your_server_name; Initial Catalog=your_database_name; User ID=your_username; Password=your_password;"
      sql = "SELECT COUNT(*) AS RecordCount FROM your_table_name"
      Set rs = conn.Execute(sql)
      If Not rs.EOF Then
          Response.Write "Total Records: " & rs("RecordCount")
      End If
      rs.Close
      Set rs = Nothing
      conn.Close
      Set conn = Nothing

2、查询特定条件下的数据条数：在WHERE子句中添加条件，可查询满足特定条件的记录数，查询计算机系的学生人数（假设学号是主键），可以使用以下代码：

**C#代码示例

      string strSQL = "SELECT COUNT(*) FROM students WHERE dept='计算机'";
      SqlCommand comm = new SqlCommand(strSQL, conn);
      int count = Convert.ToInt32(comm.ExecuteScalar());
      Response.Write("Total Computer Students: " + count);

VB代码示例

      sql = "SELECT COUNT(*) AS RecordCount FROM students WHERE dept='计算机'"
      Set rs = conn.Execute(sql)
      If Not rs.EOF Then
          Response.Write "Total Computer Students: " & rs("RecordCount")
      End If

二、使用DataTable和DataSet查询数据条数

1、填充DataTable后获取行数：先通过SELECT语句将数据填充到DataTable中，然后使用DataTable.Rows.Count属性获取记录数。

**C#代码示例

      string strSQL = "SELECT * FROM your_table_name";
      SqlDataAdapter da = new SqlDataAdapter(strSQL, conn);
      DataTable dt = new DataTable();
      da.Fill(dt);
      int rowCount = dt.Rows.Count;
      Response.Write("Total Rows in DataTable: " + rowCount);

VB代码示例

      Dim conn As New SqlConnection("your_connection_string")
      Dim dt As New DataTable()
      Dim da As New SqlDataAdapter("SELECT * FROM your_table_name", conn)
      da.Fill(dt)
      Dim rowCount As Integer = dt.Rows.Count
      Response.Write("Total Rows in DataTable: " & rowCount)

2、使用DataSet统计行数：如果使用DataSet保存查询结果，可以通过dataset.Tables[0].Rows.Count来获取记录数。

**C#代码示例

      string strSQL = "SELECT * FROM your_table_name";
      SqlDataAdapter da = new SqlDataAdapter(strSQL, conn);
      DataSet ds = new DataSet();
      da.Fill(ds, "your_table_name");
      int rowCount = ds.Tables[0].Rows.Count;
      Response.Write("Total Rows in DataSet: " + rowCount);

VB代码示例

      Dim conn As New SqlConnection("your_connection_string")
      Dim ds As New DataSet()
      Dim da As New SqlDataAdapter("SELECT * FROM your_table_name", conn)
      da.Fill(ds, "your_table_name")
      Dim rowCount As Integer = ds.Tables(0).Rows.Count
      Response.Write("Total Rows in DataSet: " & rowCount)