数据库操作类的封装

        public static string conString = @"Server=localhost;Integrated Security=True; Database=northwind";

1. 执行Sql语句, 返回受影响的行数

        string conString = @"Server=localhost;Integrated Security=True; Database=northwind";
        //执行SQL语句, 返回受影响的行数
        public int ExecuteSql(string strSql)
        {
            SqlConnection thisConnection = new SqlConnection(conString);
            SqlCommand thisCommand = new SqlCommand(strSql, thisConnection);
            thisConnection.Open();
            int rows = thisCommand.ExecuteNonQuery();
            thisConnection.Close();
            return rows;
        }

调用方法:

        string strSql=@"select * from Customers";
        int rows = ExecuteSql(strSql);

不知道为什么, 测试了一下, 返回的rows竟然是-1. 暂时没有找到原因.

2. 执行查询语句, 返回DataSet

        //执行SQL语句,返回DataSet
        public static DataSet Query(string strSql)
        {
            SqlConnection thisConnection = new SqlConnection(conString);
            DataSet thisDataSet = new DataSet();
            thisConnection.Open();
            SqlDataAdapter thisAdapter = new SqlDataAdapter(strSql, conString);
            thisAdapter.Fill(thisDataSet, "ds");
            thisConnection.Close();
            return thisDataSet;
        }

调用方法:

        string strSql = @"select * from Customers";
        DataSet ds = Utility.Query(strSql);

3. 执行一条计算查询结果语句, 返回查询结果(object)

        //执行一条计算查询结果语句,返回查询结果(object)
        public static object GetSingle(string strSql)
        {
            SqlConnection thisConnection = new SqlConnection(conString);
            SqlCommand thisCommand = new SqlCommand(strSql, thisConnection);
            thisConnection.Open();
            object obj = thisCommand.ExecuteScalar();
            if((Object.Equals(obj,null))||(Object.Equals(obj,System.DBNull.Value)))
            {
                return null;
            }
            else
            {
                return obj;
            }
        }

调用方法:

        string strSql = @"select * from Customers";
        string num = Utility.GetSingle(strSql).ToString();

5. 带参数, 执行SQL语句, 返回影响的记录数
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