• dataset 用法(2)


    1、为DataTable添加列 

    (1)添加列

    DataTable  tbl = ds.Tables.Add("User");

    DataColumn col =tbl.Columns.Add("UserID",typeof(int));

    col.AllowDBNull = false;

    col.MaxLength = 6;

    col.Unique = true;

    tbl.PrimaryKey = new DataColumn[]{tbl.Columns["UserID"]};

        当设置主键时,AllowDBNull自动设置为False;

    (2)添加自增列

    DataSet ds = new DataSet();

    DataTable tbl = ds.Tables.Add("User");

    DataColumn col = tbl.Columns.Add("UserID",typeof(int));

    col.AutoIncrement = true;

    col.AutoIncrementSeed = -1;

    col.AutoIncrementStep = -1;

    col.ReadOnly = true;

    2、修改DataTable中的数据

    (1)添加数据行

    DataRow row = ds.Tables["User"].NewRow();

    row["UserID"] = "123456";

    ds.Tables["User"].Rows.Add(row);

    object[] aValues ={"123456","张三"}

    da.Tables["User"].LoadDataRow(aValues,false);

    (2)修改当前行 

        修改行的内容 Datast并不会自动修改数据库中相应的内容,而是要使用SqlDataAdapter对象的Update方法来提交修改。

    //查找UserID为123456的用户,有则修改

    DataRow   User;

    User = ds.Tables["UserID"].Rows.Find("123456");

    if(User == null)

    //没有查找客户

    else

    {

    User.BeginEdit();

    User["UserName"] ="王五";

    User.EndEdit();

    }

    obejct[]  User ={null,”王五”} ;//null表示不修改该列的数据

    DataRow rowUser;

    rowUser = ds.Tables["UserID"].Rows.Find("123456");

    rowUser.ItemArray = User;

    (3)处理行中的空值 

    A:查看是否为空

    DataRow rowUser;

    rowUser = ds.Tables["UserID"].Rows.Find("123456");

    if(rowUser.IsNull("Address"))

    Console.WriteLine("Address is Null");

    else

    Console.WriteLine("Address is not Null");

    B:赋予空值

    rowUser["Address"] = DBNull.Value;

    (4)删除行 

    DataRow rowUser;

    rowUser = ds.Tables["UserID"].Rows.Find("123456");

    rowUser.Delete();

    (5)清除DataRow 

    A:

    DataRow rowUser;

    rowUser = ds.Tables["UserID"].Rows.Find("123456");

    rowUser.ItemArray = aUser;

    da.Tables["User"].Remove(rowUser);

    B:

    ds.Tables["User"].RemoveAt(intIndex);

    3、实例

    using System;

    using System.Collections.Generic;

    using System.Text;

    using System.Data.SqlClient;

    using System.Data;

    namespace sqlconnection1

    {

    class Program

    {

    private void SQLConnectionF(string source, string select)

    {

    //创建连接

    SqlConnection con = new SqlConnection(source);

    SqlDataAdapter adapt = new SqlDataAdapter(select,con);

    try

    {

    con.Open();

    Console.WriteLine("connection is successful!");

    }

    catch (Exception e)

    {

    Console.WriteLine("connection error is :{0}", e.ToString());

    }

    SqlCommandBuilder mybuilder = new SqlCommandBuilder(adapt);

    //创建DataSet

    DataSet ds = new DataSet();

    //将数据添加到DataSet中

    adapt.Fill(ds,"mytest");

    //取出mytest表各列名

    Console.WriteLine("{0,-15} {1,-10} {2,-10}",ds.Tables["mytest"].Columns[0],

    ds.Tables["mytest"].Columns[1], ds.Tables["mytest"].Columns[2],

    ds.Tables["mytest"].Columns[3], ds.Tables["mytest"].Columns[4]);

    //输出DataSet中的所有数据

    Console.WriteLine("before up data");

    foreach (DataRow row in ds.Tables["mytest"].Rows)

    {

    Console.WriteLine("{0,-35} {1,-10} {2,-10} {3}",row[0] ,

    row[1] , row[2] , row[3]);

    }

    //将第一行的第四列的值修改为123

    DataRow rows1 = ds.Tables["mytest"].Rows[0];

    rows1[3] = "123";

    //删除该行

    rows1.Delete();

    //插入一行

    DataRow newrow = ds.Tables["mytest"].NewRow();

    newrow[0] = "mmm";

    newrow[1] = 36;

    newrow[2] = "aaa";

    newrow[3] = 222;

    ds.Tables["mytest"].Rows.Add(newrow);

    //在DataSet中查找数据

    DataColumn[] keys = new DataColumn[2];

    keys[0] = ds.Tables["mytest"].Columns["name"];

    keys[1] = ds.Tables["mytest"].Columns["number"];

    //keys[1] = ds.Tables["mytest"].Columns ["type"];

    ds.Tables["mytest"].PrimaryKey = keys;

    DataRow findrow = ds.Tables["mytest"].Rows.Find("rrr");

    if (findrow != null)

    {

    Console.WriteLine("{0}is find in tables",findrow);

    //delete the row

    Console.WriteLine("removing the rows ........");

    findrow.Delete();

    }

    //用DataSet中的数据更新表

    adapt.Update(ds,"mytest");

    //输出DataSet中的所有数据

    Console.WriteLine("after up data");

    foreach (DataRow row in ds.Tables["mytest"].Rows)

    {

    Console.WriteLine("{0,-15} {1,-10} {2,-10} {3}", row[0],

    row[1], row[2], row[3]);

    }

    Console.ReadLine();

    con.Close();

    }

    static void Main(string[] args)

    {

    string sou = "server=duanyf\SQLEXPRESS;" + "Initial Catalog=master;" + "UID = sa;" + "Password = dyf123";

    string sel = "SELECT name,number,type,low,high From dbo.spt_values WHERE number=36";

    Program sqlcon = new Program();

    sqlcon.SQLConnectionF(sou, sel);

    }

    }

    }

    【转自】http://www.cnblogs.com/hulang/archive/2011/01/11/1932567.html

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  • 原文地址:https://www.cnblogs.com/liuruitao/p/3783825.html
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