LinQ是什么?
LinQ是语言集成的查询,是用于C#跟Vb的扩展语言
LinQ的用法
新建一个App_Code文件夹,在文件夹下添加一个数据LinQ to SQL类,可以直接直接点击服务器管理器然后就可以连接到数据库,
LinQ的增用法
using(DcDataContext dc =new DcDataContext())
{
//添加数据
dc.Users.InsertOnSubmit(us);
dc.SubmitChanges();
}
LinQ的删用法
if (listView1.SelectedItems.Count == )
{
using (DcDataContext con = new DcDataContext())
{
List<Users> ulist = con.Users.Where(r => r.Ids.ToString() == listView1.SelectedItems[].Text).ToList(); if (ulist.Count > )
{
DialogResult d = MessageBox.Show("你确定要删除吗?", "删除", MessageBoxButtons.OKCancel);
if (d == DialogResult.OK)
{
con.Users.DeleteOnSubmit(ulist[]);
con.SubmitChanges();
Sx();
} }
}
}
else
{
MessageBox.Show("请选择一项删除!");
}
LinQ修改
using (DcDataContext con = new DcDataContext())
{
Users u = con.Users.Where(r => r.Ids.ToString() == F2).FirstOrDefault();
if (u != null)
{
if (textBox1.Text == "")
{
label7.Text = "用户名不能为空!";
}
else
{
u.UserName = textBox1.Text;
} if (textBox2.Text == "")
{
label8.Text = "密码不能为空!";
}
else
{
if (textBox2.Text == textBox3.Text)
{
u.Password = textBox2.Text;
}
else
{
label8.Text = "密码不一致!";
return;
}
}
u.NickName = textBox3.Text;
if (radioButton1.Checked)
{
u.Sex = true;
}
else
{
u.Sex = false;
}
u.Birthday = dateTimePicker1.Value;
u.NationCode = comboBox1.Text;
Nation u1 = con.Nation.Where(d => d.NationName == u.NationCode).FirstOrDefault();
if (u1 != null)
{
u.NationCode = u1.NationCode;
}
con.SubmitChanges();
MessageBox.Show("修改成功!");
F1.Sx();
this.Close();
}
}
LinQ查询
模糊查询
List<Users> u = con.Users.Where(d =>d.NickName.Contains(st)).ToList();
精确查询
List<Users> u = con.Users.Where(d =>d.NickName==s).ToList();