This tutorial describes how to connect to a MySQL server with dotConnect for MySQL - dotConnect for MySQL a high-performance ADO.NET provider from Devart with ORM support. This article consists of the following sections:
In order to connect to MySQL server you need the server itself running, dotConnect for MySQL installed and IDE running. You should know server name or IP address, account login and password. Usually this information is enough.
Note that if you do not use design-time (specifically, if you do not place the MySqlConnection component from the toolbox on a form designer), you have to embed licensing information manually. This is described in dotConnect for MySQL documentation.
To establish a connection to server you have to provide some connection parameters to dotConnect for MySQL. This information is used by the MySqlConnection component to find the server and login with credentials of your account. The parameters are represented as connection string. You can compose the connection string manually or have dotConnect for MySQL construct it for you.
Note that design-time connection creation, described here, is applicable only to Windows Forms applications for Full .NET Framework.
The following assumes that you have IDE running, and you are currently focused on a form designer.
Same operations performed in runtime look as follows (note that you have to add references to Devart.Data.MySql.dll and Devart.Data.dll assemblies for Full .NET Framework or install the Devart.Data.MySql NuGet package for .NET Core):[C#]
using Devart.Data.MySql; ... MySqlConnection mySqlConnection1 = new MySqlConnection(); mySqlConnection1.Host = "127.0.0.1"; mySqlConnection1.Port = 3306; mySqlConnection1.UserId = "root"; mySqlConnection1.Password = "mypassword";[Visual Basic]
Imports Devart.Data.MySql ... Dim mySqlConnection1 As MySqlConnection = New MySqlConnection() mySqlConnection1.Host = "127.0.0.1" mySqlConnection1.Port = 3306 mySqlConnection1.UserId = "root" mySqlConnection1.Password = "mypassword"
You can do this all in single assignment. It actually does not matter whether connection string is assigned directly or composed with particular properties. After you assign a value to ConnectionString property all other properties are populated with parsed values. So you can choose what is more convenient for you.[C#]
mySqlConnection1.ConnectionString = "User Id=root;Password=mypassword;Host=127.0.0.1;";[Visual Basic]
mySqlConnection1.ConnectionString = "User Id=root;Password=mypassword;Host=127.0.0.1;"
If you decide to setup a connection by assigning values to several properties, consider using the the MySqlConnectionStringBuilder class. It has all of the possible connection settings exposed as properties, thus allowing you to customize the connection at full extent. The following example demonstrates how to compose a more complex connection string:[C#]
MySqlConnectionStringBuilder myCSB = new MySqlConnectionStringBuilder(); myCSB.Port = 3307; myCSB.Host = "localhost"; myCSB.UserId = "root"; myCSB.Password = "mypassword"; myCSB.Direct = true; myCSB.Compress = true; myCSB.Database = "demobase"; myCSB.MaxPoolSize = 150; myCSB.ConnectionTimeout = 30; MySqlConnection myConnection = new MySqlConnection(myCSB.ConnectionString);[Visual Basic]
Dim myCSB As MySqlConnectionStringBuilder = New MySqlConnectionStringBuilder myCSB.Port = 3307 myCSB.Host = "localhost" myCSB.UserId = "root" myCSB.Password = "mypassword" myCSB.Direct = True myCSB.Compress = True myCSB.Database = "demobase" myCSB.MaxPoolSize = 150 myCSB.ConnectionTimeout = 30 Dim myConnection As MySqlConnection = New MySqlConnection(myCSB.ConnectionString)
Note that in this example we used MySqlConnection constructor that accepts connection string as argument.
Besides Host, UserId and Password there is another very important property. This is Direct property. It indicates whether the MySQL client library (libmysql.dll) will be used for connecting to server. By default Direct mode is enabled, and generally it is recommended to work in Direct mode. Switch to Client mode only when you really know what do you do it for. Some features require Direct=false mode, for example, data compression.
For the information on arguments are allowed in the connection string, refer to the description of the MySqlConnection.ConnectionString property in dotConnect for MySQL documentation.
Opening a connection is as simple as that:[C#]
Of course, mySqlConnection1 must have a valid connection string assigned earlier. When you call Open, dotConnect for MySQL tries to find the host and connect to server. If any problem occurs it raises an exception with brief explanation on what is wrong. If no problem is encountered dotConnect for MySQL tries to establish the connection during ConnectionTimeout interval. Finally, when connection is established, the Open method returns and State property is changed to Open.
In design-time you can connect to server in few steps:
Or you can simply change the State property to Open in the Properties window to establish a connection using the current connection string.
To close a connection call its Close method, or set its State property to Closed.
The following example summarizes aforementioned information and shows how to create, setup, open, use and then close the connection.[C#]
MySqlConnection myConn = new MySqlConnection(); myConn.ConnectionString = "User Id=root;Password=mypassword;Host=127.0.0.1;"; myConn.Open(); MessageBox.Show(myConn.ServerVersion); myConn.Close();[Visual Basic]
Dim myConn As MySqlConnection = New MySqlConnection() myConn.ConnectionString = "User Id=root;Password=mypassword;Host=127.0.0.1;" myConn.Open() MessageBox.Show(myConn.ServerVersion) myConn.Close()
The sample code connects to a server, shows its version and then closes the connection. This actually is rare usage, because in real applications connections are used by other objects like MySqlCommand, MySqlDataTable and others. For more information on this, please see the corresponding tutorials or dotConnect for MySQL documentation.
You can modify connection by changing properties of MySqlConnection object. Keep in mind that while some of the properties can be altered freely, most of them close connection when new value is assigned. For example, if you change Server property, it gets closed immediately, and you have to reopen it manually.
This tutorial describes how you can connect to an MySQL server with dotConnect for MySQL - an ADO.NET provider from Devart with ORM support. dotConnect for MySQL has wide set of features you can take advantage of. You may take a look at other dotConnect for MySQL tutorials to learn more about them or download dotConnect for MySQL and try it yourself.