C#连接数据库

 SqlConnection conn = new SqlConnection(@"data source=20110105-1517;initial catalog=消防预警系统;User ID=sa;password=28");

数据的更新替换 update Table_1 set 姓名='张晓玲' where 姓名='牛羊'
多行替换update Table_1  set 姓名='牛永杰' ,年龄='100' where 姓名='牛永斌' and 工资=100000
排序  select 年龄 from Table_1 order by  年龄 desc
Begin end 结合使用

很多的SQL语句中要使用end结束(when @str=90 then '你的成绩是优秀'
end
print  @str1)
using System;
using System.Data;
using System.Data.SqlClient;
namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection conn = new SqlConnection(@"server=.;integrated security=true;database=db_business");
            //SqlConnection conn = new SqlConnection(@"server=.\db_business;integrated security=true;");
            string sql = @"select count (*) from  职工 ";
            SqlCommand cmd = new SqlCommand(sql,conn);

            try
            {
                conn.Open();
                Console.WriteLine("打开成功");

                Console.WriteLine("结果：{0}",cmd.ExecuteScalar());
            }
            catch (SqlException e)
            {
                Console.WriteLine("错误是：" + e);
            }
            finally
            {
                conn.Close();
                Console.WriteLine("连接关闭！");
            }
            Console.Read();

        }
    }
}

            int[] arr = { 1, 2, 3,58,110 };
            foreach (int i in arr)
            {
                System.Console.WriteLine(i);
            }

数据集，数据适配器都是构造函数重载的，
　　  string sql = @"select * from  Table_1 ";
                SqlDataAdapter da = new SqlDataAdapter (sql,conn);
                DataSet ds = new DataSet();
                da.Fill(ds,"Table_1");
                DataTable dt = ds.Tables["Table_1"];
                foreach(DataRow row in dt.Rows)
                {
                    foreach(DataColumn col in dt.Columns)
                        Console.WriteLine(row[col]);
                        Console.WriteLine("".PadLeft(20,'='));

                }

获取dataGridView1控件中的值
　　   for (int i = 0; i < dataGridView1.Columns.Count;i++ )
            {
                string str = "";
                if (i == 0)
                {
                    str += dataGridView1.Rows[e.RowIndex].Cells[i].Value.ToString();
                    textBox1.Text = str;
                }
                else
                {
                    str += dataGridView1.Rows[e.RowIndex].Cells[i].Value.ToString();
                    textBox2.Text = str;
                }
            }
 ///使用数据适配器操作数据集，并不是直接对数据库的操作，
//使用sqldataadapt 实现数据的添加
            SqlCommandBuilder sb = new SqlCommandBuilder(da);
            DataRow row = ds.Tables[0].NewRow();
            row["ID"] = "D7";
            row["AreaName"] = "测a试º?区?3";
            ds.Tables[0].Rows.Add(row);
            da.Update(ds);
            dataGridView1.DataSource = ds.Tables[0];
            conn.Close ();
//使用sqldataadapt 删除数据
          SqlCommandBuilder sqlcb = new SqlCommandBuilder(da);
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {
                if(ds.Tables[0].Rows[i][1].ToString()=="测a试º?区?2")
                {
                    ds.Tables[0].Rows[i].Delete();
                }
            }
            da.Update(ds);
//使用sqldataadapt 修改数据
          SqlCommandBuilder sqlcb = new SqlCommandBuilder(da);
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {
                if(ds.Tables[0].Rows[i][1].ToString()=="测a试º?区?3")
                {
                    ds.Tables[0].Rows[i][1]="测a试º?区?1";
                }
            }
            da.Update(ds);