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This article introduces the relevant knowledge of "what is the connection method of JDBC". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

I. the role of JDBC

The full name of JDBC is Java DataBase Connection, that is, Java database connection, which we can use to operate relational databases. The JDBC interface and related classes are in the java. SQL package and the javax.sql package. We can use it to connect to the database, execute SQL queries, stored procedures, and process the returned results.

The JDBC interface loosely couples the Java program with the JDBC driver, which makes it easier to switch between different databases.

Second, the connection steps of JDBC

Perform a JDBC connection in six steps:

1. Import package

Include the JDBC classes needed for database programming in the program. In most cases, using import java.sql.* is sufficient.

two。 Register the JDBC driver

The driver needs to be initialized so that communication with the database can be opened.

3. Open a connection

Use the DriverManager.getConnection () method to create a Connection object that represents a physical connection to a database.

4. Execute a query

You need to use an object of type Statement or PreparedStatement (see the difference below) and submit a SQL statement to the database to execute the query.

5. Extract data from the result set

This step demonstrates how to get the data of the query results from the database. The result of the data retrieved using the ResultSet.getXXX () method.

6. Clean up environmental resources

After using JDBC to interoperate with data in the database, you should explicitly close all database resources to reduce the waste of resources.

III. Best practices of JDBC

Database resources are very expensive and should be closed as soon as they are used up. Connection, Statement, ResultSet and other JDBC objects all have close methods, so just call it.

ResultSet,Statement,Connection must be explicitly closed in the code. If you are using connection pooling, connections will be put back into the pool after use, but unclosed ResultSet and Statement will cause resource leakage.

Close the resource in the finally block to ensure that it closes normally even if an exception occurs.

A large number of similar queries should be done in batches.

Try to use PreparedStatement instead of Statement to avoid SQL injection and improve execution efficiency through precompilation and caching mechanisms.

If you want to read a large amount of data into ResultSet, you should set up fetchSize reasonably to improve performance.

The database you are using may not support all isolation levels. Check carefully before using it.

The higher the database isolation level, the worse the performance. Make sure that the isolation level set by your database connection is optimal.

If you need to operate on ResultSet for a long time, try to use offline RowSet.

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