How to connect to database in java

1. Download a mysql database driver jar package from the Internet, similar to mysql-connector-java-5.1.20-bin.jar. Create a new JAVA project, create a lib folder under the project, and copy the driver jar file to the lib folder

#2. Add the JAR package to the project's build in the path variable. Right side of the mouse-》build path->configure build path.. Click Add jars in the pop-up interface, select the driver jar package and add it to the build path variable

3 , create a JAVA file and write the code to connect to the database. Four variables need to be declared (static, generally not modified). url is the network address of the database and its name. name is the name of the driver (different databases are different, fixed writing methods defined by others), user database user name password database connection password

4. Create a Connection object through the database connection, The constructor of the TestDBHelper class passes in the sql statement, so that when using it, you can directly use the New object and then pass in the SQL statement for execution. Remember to write a method to close the connection. The connection must be closed after each access to the database

5. Write the main method to test the database connection. The result set of the SQL statement execution is placed in the ResultSet In the object, if you want to get the contents inside, you need to loop out them one by one. Remember to close the database connection after use

#6. Check the output information of the console and compare it with the information in the database table to see if it is consistent. In addition, my table here only has two fields. If there are multiple fields, just follow ret.getString(2); ret.getString(3); and take them from the back.

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