C#中 sqlDataRead 的三种方式遍历读取各个字段数值

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数据库的查询分析器中写上如下代码：

ccreate table studentname
(
id int primary key identity(1,1) not null ,
name nvarchar(500) not null
)

insert into studentname values(‘long‘)

insert into studentname values(‘chao‘)

–sql server 2012 通过。

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以下是第一种方法：

using System.Data;

using System.Data.SqlClient;

string constr = “server=localhost;uid=sa;pwd=longshicheng;database=Student”;

SqlConnection conn = new SqlConnection(constr);

SqlCommand cmd = new SqlCommand(“select * from studentname”, conn);

conn.Open();

            SqlDataReader rdr = cmd.ExecuteReader();
            string makestr = “”;
            DataTable table = new DataTable();
            table.Load(rdr); //数据表装入 dataReader 。
            string result=””;
            for (int i = 0; i < table.Rows.Count; i++) // 遍历行
            {
                for (int j = 0; j < table.Columns.Count; j++) //遍历列
                {
                    result += table.Rows[i][j].ToString(); //逐行逐列显示每个单元格的数值。
                }
                result += Environment.NewLine; //一行遍历完成就写入回车。
            }
            txtlab.Text = result;

/***************************************************************/

以下是第二种方法:

string constr = “server=localhost;uid=sa;pwd=longshicheng;database=Student”;

SqlConnection conn = new SqlConnection(constr);

SqlCommand cmd = new SqlCommand(“select * from studentname”, conn);

conn.Open();

            SqlDataReader rdr = cmd.ExecuteReader();
            string makestr = “”;
            for (int k = 0; k < rdr.FieldCount; k++) //获取字段名称
            {
                makestr += rdr.GetName(k) + “\t”; //载入字段名称
            }
            makestr += Environment.NewLine; //换行
            makestr = makestr + “———————————————“+Environment.NewLine;
            while (rdr.Read()) //逐行读取每一笔记录
            {
                for (int t = 0; t < rdr.FieldCount; t++) //逐列读出
                {
                    makestr = makestr + rdr[t].ToString() + “\t”; //累加每一行，也就是逐个字段读出对应的数值
                }
                makestr = makestr + Environment.NewLine; //又一行
            }
            txtinfo.Text = makestr;
            rdr.Close(); //关闭
            conn.Close();
        }

以下是第三种方法：

string constr = “server=localhost;uid=sa;pwd=longshicheng;database=Student”;

SqlConnection conn = new SqlConnection(constr);

SqlCommand cmd = new SqlCommand(“select * from studentname”, conn);

conn.Open();

            SqlDataReader rdr = cmd.ExecuteReader();
            string makestr = “”;

            for (int k = 0; k < rdr.FieldCount; k++) //获取字段名称
            {
                makestr += rdr.GetName(k) + “\t”; //载入字段名称
            }
            makestr += Environment.NewLine; //换行
            makestr = makestr + “———————————————” + Environment.NewLine;
            while (rdr.Read()) //逐行读取每一笔记录
            {
                makestr = makestr + rdr.GetValue(0) + ” \t” + rdr.GetValue(1).ToString() + “\t”;
                makestr = makestr + Environment.NewLine;
            }
            txtother.Text = makestr;
            rdr.Close(); //关闭
            conn.Close();

以上所有方法运行结果均如下：

id   name
———————————————
1    long
2    long
3    long
4    long
5    long
6    chao
7    chao