如何使用MySQL进行高效的数据查询？

CREATE INDEX idx_name ON user_info (name);

SELECT * FROM user_info WHERE age >= 18;

SELECT * FROM user_info WHERE name LIKE '张%';

SELECT * FROM user_info LIMIT 0, 10;

SELECT * FROM user_info WHERE age >= 18;
SELECT * FROM user_info WHERE name LIKE '张%';

SELECT * FROM user_info WHERE age >= 18 OR name LIKE '张%';

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class ConnectionPool {
    private static final String URL = "jdbc:mysql://localhost:3306/mydb";
    private static final String USER = "root";
    private static final String PASSWord = "password";

    private static Connection connection;

    private ConnectionPool() {
    }

    public static synchronized Connection getConnection() {
        if (connection == null) {
            try {
                connection = DriverManager.getConnection(URL, USER, PASSWORD);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return connection;
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class Main {
    public static void main(String[] args) {
        Connection connection = ConnectionPool.getConnection();
        try {
            PreparedStatement statement = connection.prepareStatement("SELECT * FROM user_info WHERE age >= ?");
            statement.setInt(1, 18);
            ResultSet resultSet = statement.executeQuery();
            while (resultSet.next()) {
                // 处理查询结果
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}