针对各种不同的数据库应用环境,ADO.NET提供了四种数据库提供程序,这四种数据库提供程序位于不同的命名空间,但是它们的组成结构相同,使用方法相似。本实验要求利用VS2003平台对SQL2000进行数据库的查询操作。
无论式那种模式,操纵数据库的步骤都一样:
1、确立查询语句:
select * from job where min_lvl >20
结果如下:
job_id job_desc min_lvl max_lvl
------ -------------------------------------------------- ------- -------
3 Business Operations Manager 176 225
4 Chief Financial Officier 176 250
5 Publisher 151 250
6 Managing Editor 141 225
7 Marketing Manager 121 200
8 Public Relations Manager 103 175
9 Acquisitions Manager 78 175
10 Productions Manager 78 165
11 Operations Manager 78 150
12 Editor 28 100
13 Sales Representative 28 100
14 Designer 28 100
(所影响的行数为 12 行)
2、建立连接
3、建立Command对象
4、执行
5、显示结果
1、在线式非存储过程方式查询数据
//SQL认证模式的建立连接代码如下
//using( SqlConnection sc = new SqlConnection("server =192.168.8.66;database = pubs;uid = sa;pwd = sa;") )
//Windows集成认证模式的建立连接代码如下
using(SqlConnection sc = new SqlConnection("server = .;database = pubs;trusted_connection = sspi;"))
{//执行可能抛出异常的代码
try
{//打开数据库连接
sc.Open();
//实例化命令对象
SqlCommand com =new SqlCommand("select * from job where min_lvl >20",sc);
com.CommandType = ommandType.Text;
//只读向前的方式显示数据
SqlDataReader sr = com.ExecuteReader();
while(sr.Read())
{
Console.WriteLine(sr[0]);
}
}
catch(Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
if(sc.State ==ConnectionState.Open)
sc.Close();
}
}
2、在线式存储过程方式查询数据
创建存储过程:
USE pubs
--如果存在Sel存储过程,则将其删除
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'Sel' AND type = 'P')
DROP PROCEDURE Sel
GO
create proc Sel
(@con int)
as
select * from job where min_lvl < @con
显示代码:
//using( SqlConnection sc = new SqlConnection("server =192.168.8.66;database = pubs;uid = sa;pwd = sa;") )
using(SqlConnection sc = new SqlConnection("server = .;database = pubs;trusted_connection = sspi;"))
{
try
{
sc.Open();
//指明存储过程的过程名和连接对象
SqlCommand com =new SqlCommand("sel",sc);
//指明命令对象的执行命令类型
com.CommandType = CommandType.StoredProcedure;
//为命令对象添加参数对象
/*
需要指明参数对象的存储过程变量名"@con",数据类型SqlDbType.Int
*/
SqlParameter sp = new SqlParameter("@con",SqlDbType.Int);
//设定值
sp.Value =20;
//设定传值方向
sp.Direction = ParameterDirection.Input;
//为命令对象添加参数对象
com.Parameters.Add(sp);
//执行命令
SqlDataReader sr = com.ExecuteReader();
while(sr.Read())
{//遍历数据
Console.WriteLine(sr[0]);
}
}
catch(Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
if(sc.State ==ConnectionState.Open)
sc.Close();
}
3、断开式非存储过程方式查询数据
//实例化sqlcommand对象
this.sqlSelectCommand1.CommandText ="SELECT id, name, sex, email FROM stuinfo";
this.sqlSelectCommand1.Connection = this.sqlConnection1;
//为数据适配器设置查询命令对象
this.sqlDataAdapter1.SelectCommand = this.sqlSelectCommand1;
//绑定数据源
this.dataGrid1.DataSource =this.dataSet11;
this.dataGrid1.DataMember = "stuinfo";
//填充数据集
this.sqlDataAdapter1.Fill(this.dataSet11);
4、断开式存储过程方式查询数据
//实例化sqlcommand对象,步骤二完全类似
this.sqlSelectCommand1.CommandText = "Sel";
this.sqlSelectCommand1.CommandType = CommandType.StoredProcedure;
SqlParameter sp = new SqlParameter("@con",SqlDbType.Int);
sp.Value =20;
sp.Direction = ParameterDirection.Input;
this.sqlSelectCommand1.Parameters.Add(sp);
this.sqlSelectCommand1.Connection = this.sqlConnection1;
//为数据适配器设置查询命令对象
this.sqlDataAdapter1.SelectCommand = this.sqlSelectCommand1;
//绑定数据源
this.dataGrid1.DataSource =this.dataSet11;
this.dataGrid1.DataMember = "stuinfo";
//填充数据集
this.sqlDataAdapter1.Fill(this.dataSet11);