SQL database--data access

Data access:

corresponding namespaces:System.Data.SqlClient;

SqlConnection: Connection Object

SqlCommand: Command Object

SqlDataReader: Reader Object

Create a connection string

String connstring = "server=.; Database=mydb;user=sa;pwd=123 ";

Connecting Objects

SqlConnection conn = new SqlConnection (connstring);

To Create a Command object

SqlCommand cmd = conn. CreateCommand ();

write the SQL statement to execute

Cmd.commandtext = "SELECT * from Info";

Open Connection

Conn. Open ();

perform operation (read operation, return reader object)

SqlDataReader dr = cmd. ExecuteReader ();

Perform operation (add-and-revise operation, return number of rows)

Cmd. ExecuteNonQuery ();

working with Data

if (Dr. HasRows)--This is a Boolean-type value that returns True or false

{

Dr. Read ();

Console.WriteLine (Dr[0]);

Console.ReadLine ();

}

Else

{

Console.WriteLine (" Read failed! ");

}

Close Connection

Conn. Close ();

Dr. Read () is a database data access pointer that goes down one line each time it executes, returns true if there is content , and Dr Access is the current row data collection. You can use an index or column name to access the corresponding data

SQL database--data access