DataSet用法(三) 操作数据

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);

}

}

}