Using HSQLDB for embedded database processing in Java API development

With the popularity of Web applications, the demand for databases is getting higher and higher. In order to better meet user needs, developers have designed a variety of database operation tools. With the development of the Java language, the use of embedded databases in applications has gradually increased. This article will introduce in detail how to use HSQLDB for embedded database processing in Java API development.

1. What is HSQLDB

HSQLDB is a lightweight, self-contained embedded database management software written in Java language and can be used on any hardware and operating system that supports Java and run on JVM.

HSQLDB provides a reliable, widely supported open source database engine that can be used not only as a standalone application, but also as an embedded database integrated into Java applications. HSQLDB features automatic failure detection, recovery and data integrity and is available in different operating modes.

At the same time, it also provides a variety of interfaces for Java programmers to use, such as JDBC API, SQL interface and integrated development environments such as NetBeans.

2. Using HSQLDB

Before using HSQLDB, we need to understand some basic concepts and usage methods.

1. Installation of HSQLDB

HSQLDB, as an embedded database, requires us to install it using the Jar package it provides. We can find the relevant Jar package in the Maven repository and introduce it into our project through the following code:

<dependency>
    <groupId>org.hsqldb</groupId>
    <artifactId>hsqldb</artifactId>
    <version>2.5.1</version>
</dependency>

2. HSQLDB startup and connection

For HSQLDB startup and connection To connect, we can use the following code:

// 启动HSQLDB
Server server = new Server();
server.setNoSystemExit(true);
server.setDatabaseName(0, "mydb");
server.setDatabasePath(0, "file:~/mydb");
server.start();

// 连接HSQLDB
Connection conn = DriverManager.getConnection("jdbc:hsqldb:file:~/mydb", "SA", "");

Among them, we can use the Server class to start HSQLDB, and specify the location of the database by setting databasePath. After starting the service, we You can connect to the database through the JDBC API.

3. HSQLDB operation

HSQLDB supports standard SQL language, we can use JDBC API for database operations, for example:

// 创建表
Statement stmt = conn.createStatement();
stmt.execute("CREATE TABLE USER (ID INT, NAME VARCHAR(20), AGE INT)");

// 插入数据
PreparedStatement ps = conn.prepareStatement("INSERT INTO USER (ID, NAME, AGE) VALUES (?, ?, ?)");
ps.setInt(1, 1);
ps.setString(2, "张三");
ps.setInt(3, 20);
ps.executeUpdate();

// 查询数据
ResultSet rs = stmt.executeQuery("SELECT * FROM USER");
while (rs.next()) {
    int id = rs.getInt("ID");
    String name = rs.getString("NAME");
    int age = rs.getInt("AGE");
    System.out.println(id + "    " + name + "    " + age);
}

In addition to basic queries In addition to update operations, HSQLDB also provides many other advanced features, such as transaction processing and indexing.

3. Notes

When using HSQLDB, we need to pay attention to the following points:

1. Data types of HSQLDB

The data types supported by HSQLDB are not exactly the same as the standard SQL data types. Some data types are unique to HSQLDB, such as BOOLEAN, IDENTITY and VARCHAR_IGNORECASE, etc. . Therefore, when defining the table structure, you need to pay attention to whether the data type used is compatible with standard SQL.

2. HSQLDB connection method

HSQLDB supports multiple connection methods, including file:,mem:,res:, http:, https:, etc. When using the same connection method, the database name must be consistent.

3. How to start HSQLDB

HSQLDB can be started as a service or directly in the application as an embedded database. In practical applications, we can choose different startup methods according to specific needs.

4. Summary

This article introduces the method of using HSQLDB for embedded database processing in Java API development. As a lightweight, self-contained embedded database management software, HSQLDB not only provides a rich database operation interface, but also has automatic fault detection, recovery and data integrity features. In actual development, we can select the corresponding startup method and connection method according to specific needs to meet different application scenarios.

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