c#连接Sqlserver数据库

一层一层的调用

一层SqlConnction连接数据库

二层SqlCommand执行SQL语句

三层SqlDataAdapter填充DataSet或者DataSet

四层DataSet  这是一个表的集合DataTable是他的一个表，

五层DataTable

六层DataRow DataColumn

SqlCommandBuilder用于生成SQl语句更新数据库

例：

SqlConnection conn=new SqlConnection("Data Source=.\\SQLEXPRESS;Initial Catalog = EmployeeDB; Integrated Security=True");

SqlCommand cmd=new SqlCommand("select *",conn);

/*

SqlCommand cmd=new SqlCommand(conn);

cmd.Connection=conn;

*/

/*

SqlCommand cmd=new SqlCommand();

cmd.Connection=conn;

cmd.CommandText="select *";

*/

/*

SqlDataAdapter adapter = new SqlDataAdapter("select *", “Data Source=.\\SQLEXPRESS;Initial Catalog = EmployeeDB; Integrated Security=True”);//可以直接避开SqlCommand直接用SqlDataAdapter

*/

/*

SqlDataAdapter adapter = new SqlDataAdapter("select *", Conn);

*/

/*

SqlDataAdapter adapter = new SqlDataAdapter(cmd);

*/

SqlDataAdapter adapter = new SqlDataAdapter();

adapter.SelectCommand=cmd;

SqlCommandBuilder builder = new SqlCommandBuilder(adapter);//加上这一句话，在更新数据库之前
DataSet ds = new DataSet();
adapter.Fill(ds, "Titles");