Introduction to Java basics to practical applications: practical database operations

Introduction to Java Basics covers data types, variables, operators and control flow. JDBC is an API for interacting with databases, executing SQL queries and managing connections. Practical example steps: load the driver, create the database connection, create the statement object, execute the SQL query, process the result set, and finally close the connection.

Java Basics to Practical Application: Database Practical Operation

Introduction

Java is a powerful object-oriented programming language that is widely used in various application development. Mastering the basics of Java is critical to building efficient, maintainable software. This article introduces the basics of Java and walks you through a hands-on example using a database.

Basic knowledge

• Data types: Java provides various data types, including primitive data types (int, long, float etc.) and object types (String, ArrayList, etc.).
• Variable: Identifier used to store the value.
• Operators: Used to perform arithmetic, comparison and logical operations.
• Control flow: If-else, switch, while, for and other statements are used to control the program flow.

Interacting with the database

JDBC (Java Database Connectivity) is an API used to communicate with a database in a Java program. It allows you to execute SQL queries, update database records, and manage database connections.

Practical Example

The steps to use JDBC to connect to the database and execute queries are as follows:

1. Load the JDBC driver

//假设您使用的是 MySQL 数据库
Class.forName("com.mysql.jdbc.Driver");

2. Create database connection

Connection connection = DriverManager.getConnection(
    "jdbc:mysql://localhost:3306/mydb", "username", "password");

3. Create statement object

Statement statement = connection.createStatement();

4. Execute SQL Query

ResultSet resultSet = statement.executeQuery(
    "SELECT name, email FROM users WHERE id = 1");

5. Process the result set

while (resultSet.next()) {
    String name = resultSet.getString("name");
    String email = resultSet.getString("email");
    //处理结果...
}

6. Close the database connection

resultSet.close();
statement.close();
connection.close();

Conclusion

This tutorial introduced Java basics and JDBC, and provided practical examples of using JDBC to perform database operations.

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