When I first came into contact with using JDBC to connect to a database, I always encountered a lot of problems, making people confused. Therefore, I use SQL Server

As an example, explain in detail how to use JDBC to connect to SQL Server. Click to downloadSQL Server 2017、SQL Server 2016

Tomcat 9.0.1

Before starting, please install SQL Server and Tomcat correctly. (The author uses SQL Server 2017 and Tomcat9.0.1 to demonstrate)

Preparation: After installing SQL server and Tomcat correctly, open cmd and run the command "telnet 127.0.0.1 1433", if it appears

"Telnet is not an internal command or program..." means you have not opened the telnet service, then please refer to another blog of the author"Open telnet service problem"

If you open the telnet service correctly, but run the above telnet command, "cannot connect to 127.0.0.1, port 1433..." appears, it means that you need to

Server configuration, the next step is the detailed configuration process.

first step:Use the keyboard shortcut "window+x" to select "Computer Management" or directly use SQL Server Configuration Manager, as shown in the figure:

The second step:The opened window is shown in the figure below. Find in the left column SQL ServerNetwork configuration option, click on its small arrow, it will

See "[Your database name] agreement" , Select it and look at the right column. As shown:

third step:If Named Pipes Not enabled, then right click → enable,Right-click TCP/IP,select Enable,Double click TCP/IP

(Right click→Properties), select in the pop-up window “IPaddress" Tab, set IP1And the [IP address] of IP10 is set to 127.0.0.1,

And set all 【IPx】【enabled】to yes. Then, drag the drop-down bar to the bottom, IPAll [TCPPort] Set

to make 【1433], the rest remain unchanged. As shown:

the fourth step:Restart the computer,Next use telnetThe command "telnet 127.0.0.1 1433" tests whether port 1433 is open.

the fifth step:Environment variable CLASSPATHConfiguration: DownloadJDBC,thenIn DCreate a new folder on the disk, name it sqljdbc4, and change

Copy sqljdbc42.jar into it.

The sixth step:Right click my computer → Attributes → Advanced system settings (advanced) → Environment variables, double click in the system variables

CLASSPATHVariable (or after selecting CLASSPATH → Edit), append at the end “;D:\sqljdbc42\sqljdbc42.jar” 

(Note that there is a ; ) If CLASSPATH does not exist, Create a new CLASSPATH variable and set its value

It is "D:\sqljdbc42\sqljdbc42.jar".Continuous click determine To exit the environment variable configuration.

Step Seven:(Very important)We need to add sqljdbc4.jarCopy the class library file to D:\Java Tools\jdk1.7.0\jre\lib\ext

Mark down. (It depends on which drive you install on, if it is drive C, the first D is changed to C, the same below).

We need to add sqljdbc42.jarCopy the class library files to the D:\Program Files\Java\jre7\lib\ext directoryPreferably, as long as

Is jreFolder, copy a sqljdbc42.jar to jre7\lib\ext! !

If you are using TomcatAs a server (I use Tomcat7), then we need to add the sqljdbc42.jar class library file

Copy it to the D:\Tomcat_9.0.1\lib directory.

The eighth step:Open SQL Server 2017To create a new database Test, And then exit SQL Server2017。

Run Eclipse, Create a new JavaProject Named Test。Right click on src, Select Build Path → Configure Build Path,in

Select on the right side of the opened window LibrariesTab and click Add External JARs,turn up sqljdbc42.jar File and type

Open and click OK Complete the configuration of the build path. As shown:

Finally: enter the code to test

importjava.sql.*;
 
publicclass Main {
 publicstatic void main(String [] args)
 {
  StringdriverName="com.microsoft.sqlserver.jdbc.SQLServerDriver";
  StringdbURL="jdbc:sqlserver://localhost:1433;DatabaseName=Your database name";
     String userName="Fill in your username, mine is sa";
     String userPwd="Fill in your password";
  try
  {
   Class.forName(driverName);
   ConnectiondbConn=DriverManager.getConnection(dbURL,userName,userPwd);
         System.out.println("Connect to the database successfully");
  }
  catch(Exception e)
  {
   e.printStackTrace();
       System.out.print("Connection failed");
  }    
 }
}