C # code set connecting six classes of databases __ database

C # code set connecting six classes of databases

This article lists the source code and points to note for C # 's programs connecting access, SQL Server, Oracle, MySQL, DB2, and Sybase six different databases.

1.c# Connect to access

Program code:

Using System.Data; Using System.Data.OleDb; .. String strconnection= "provider=microsoft.jet.oledb.4.0;"; strconnection+=@ "Datasource=c:begaspnetnorthwind.mdb"; OleDbConnection objconnection=new OleDbConnection (strconnection); .. Objconnection.open (); Objconnection.close ();

Explain:

Connecting to an Access database requires importing additional namespaces, so it is essential that you have the first two using command!

Strconnection This variable holds the connection string required to connect to the database, specifying the data provider to use and the data source to use.

"Provider=Microsoft.Jet.OLEDB.4.0;" Refers to the data provider, which uses the Microsoft Jet engine, which is the data engine in access, that ASP.net is connected to the Access database.

"Data Source=c:/begaspnet/northwind.mdb" is the location that indicates the data source, and his standard form is "Data Source=mydrive:mypath/myfile.mdb".

Ps:
1. The "@" symbol after "+ =" is to prevent the "/" in the following string from being resolved to an escape character.
2. If the database file you want to connect to is in the same directory as the current file, you can also connect by using the following methods:

strconnection+= "Data source="; Strconnection+=mappath ("Northwind.mdb");

3. Be aware that the parameters in the connection string are separated by semicolons.

"OleDbConnection objconnection=new OleDbConnection (strconnection);" This is the use of a defined connection string to create a linked object, the future operation of the database we have to deal with this object.

"Objconnection.open ();" This is used to open the connection. At this point, the connection to the Access database is complete.

2.c# Connect SQL Server

Program code:

Using System.Data; Using System.Data.SqlClient; .. String strconnection= "user id=sa;password=;"; strconnection+= "Initial catalog=northwind; Server=yoursqlserver; "; strconnection+= "Connect timeout=30"; SqlConnection objconnection=new SqlConnection (Strconnection); .. Objconnection.open (); Objconnection.close ();

Explain:

The mechanism for connecting to a SQL Server database is not much different from the mechanism for connecting to access, except that different parameters in the Connection object and the connection string are changed.

First, the namespace used to connect to SQL Server is not "System.Data.OleDb", but "System.Data.SqlClient".

And then there's his connection string, and we'll introduce a parameter (note: Separate the parameters by semicolons):
' User Id=sa ': The authentication user name for the connection database is SA. He also has an alias "UID", so we can also write "Uid=sa".
"Password=": The authentication password for the connection database is empty. His alias is "pwd", so we can write it as "pwd=".
Note here that your SQL Server must have been set up with a username and password to log in, otherwise you won't be able to log in this way. If your SQL Server is set up for Windows logon, you do not need to use the "User ID" and "password" method to log in, and you need to use "TRUSTED_CONNECTION=SSPI" to log in.
"Initial Catalog=northwind": The data source used is the "Northwind" database. His alias is "Database", this sentence can be written as "Database=northwind".
"Server=yoursqlserver": Use a server named "YourSQLServer". His alias is "Data Source", "Address", "Addr". If you are using a local database and the instance name is defined, you can write as server=/instance name and, if it is a remote server, replace "(local)" with the name or IP address of the remote server.
"Connect timeout=30": Connection timeout is 30 seconds.

Here, the constructor used to establish the connection object is: SqlConnection.

3.c# Connect Oracle

Program code:

Using System.Data.OracleClient; Using System.Data; //Add a button on the form, called Button1, double-click Button1, and enter the following code private void Button1_Click (object sender, System.EventArgs e) { string connectionstring= ' Data Source=sky; User=system;password=manager; "; ///write connection string OracleConnection conn=new oracleconnection (ConnectionString); //Create a new connection try {conn. Open (); OracleCommand Cmd=conn. CreateCommand (); cmd.commandtext= "SELECT * from MyTable"; //Write SQL statements here OracleDataReader Odr=cmd. ExecuteReader (); //Create a Oracledatereader object while (ODR). Read ()) //reads data, if the ODR. If Read () returns to false, it shows the end of the recordset            { Response.Write (ODR. Getoraclestring (1). ToString ()); //Output field 1, this number is the field index, specifically how to make Using field names is still to be studied ODR. Close (); } catch (Exception ee) { Response.Write (EE. message); If there is an error, output error information } finally { Conn. Close (); Close the connection }

4.c# connection MySQL

Program code:

Using Mysqldrivercs; Establishing a database connection Mysqlconnection Dbconn; Dbconn = new Mysqlconnection (New mysqlconnectionstring ("localhost", "MySQL", "Root", "", 3306). asstring); Dbconn.open (); Executing query statements Mysqlcommand Dbcomm; Dbcomm = new Mysqlcommand ("Select Host,user from User", dbconn); Reading data Mysqldatareader dbreader = Dbcomm.executereaderex (); Display data Try { while (Dbreader.read ()) { Console.WriteLine ("Host = {0} and User = {1}") Dbreader.getstring (0), dbreader.getstring (1)); } } Finally { Dbreader.close (); Dbconn.close (); } To close a database connection Dbconn.close ();

5.c# Connect IBM DB2

Program code:

Oledbconnection1.open (); Open a database connection Oledbdataadapter1.fill (DataSet1, "address"); Fill in the dataset with the data you have obtained Datagrid1.databind (); Binding Data Oledbconnection1.close (); Close connection Increase database data Add a TextBox to the number of fields on the Web form, and a button, add the Click Response event code for the key button as follows: This.OleDbInsertCommand1.CommandText = "Insertsintosaddress" (NAME, EMAIL, age, address) VALUES (' +textbox1.text+ ', ' "+textbox2.text+", ' +textbox3.text+ ', ' +textbox4.text+ ' '; OleDbInsertCommand1.Connection.Open (); Open connection Oledbinsertcommand1.executenonquery (); Execute the SQL statement OleDbInsertCommand1.Connection.Close (); Close connection

6.c# Connect Sybase

Program code:

Provider=sybase.aseoledbprovider.2; Initial catalog= database name; User id= username; data source= datasource; Extended properties= ""; Server NAME=IP address; Network Protocol=winsock; Server Port address=5000;