Mybatis三种批量插入数据的方式
https://www.jb51.net/article/210089.htm
这篇文章主要介绍了Mybatis的三种批量插入方式，帮助大家更好的理解和学习使用Java，感兴趣的朋友可以了解下
目录
1. 循环插入
mapper.xml：
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<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.buhe.demo.mapper.StudentMapper"> <insert id="insert" parameterType="Student"> INSERT INTO tb_student (name, age, phone, address, class_id) VALUES (#{name},#{age},#{phone},#{address},#{classId}) </insert></mapper> |
mapper接口：
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public interface StudentMapper { int insert(Student student);} |
测试代码：
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@SpringBootTestclass DemoApplicationTests { @Resource private StudentMapper studentMapper; @Test public void testInsert(){ //数据生成 List<Student> studentList = createData(100); //循环插入 long start = System.currentTimeMillis(); studentList.stream().forEach(student -> studentMapper.insert(student)); System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){ List<Student> studentList = new ArrayList<>(); Student student; for(int i = 0; i < size; i++){ student = new Student(); student.setName("小王" + i); student.setAge(18); student.setClassId(1); student.setPhone("1585xxxx669"); student.setAddress("未知"); studentList.add(student); } return studentList; }} |
2. foreach标签
mapper.xml：
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<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.buhe.demo.mapper.StudentMapper"> <insert id="insert" parameterType="Student"> INSERT INTO tb_student (name, age, phone, address, class_id) VALUES (#{name},#{age},#{phone},#{address},#{classId}) </insert> <insert id="insertBatch"> INSERT INTO tb_student (name, age, phone, address, class_id) VALUES <foreach collection="list" separator="," item="item"> (#{item.name},#{item.age},#{item.phone},#{item.address},#{item.classId}) </foreach> </insert></mapper> |
mapper接口：
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public interface StudentMapper { int insert(Student student); int insertBatch(List<Student> studentList);} |
测试代码：
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@SpringBootTestclass DemoApplicationTests { @Resource private StudentMapper studentMapper; @Test public void testInsertByForeachTag(){ //数据生成 List<Student> studentList = createData(100); //使用foreach标签，拼接SQL插入 long start = System.currentTimeMillis(); studentMapper.insertBatch(studentList); System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){ List<Student> studentList = new ArrayList<>(); Student student; for(int i = 0; i < size; i++){ student = new Student(); student.setName("小王" + i); student.setAge(18); student.setClassId(1); student.setPhone("1585xxxx669"); student.setAddress("未知"); studentList.add(student); } return studentList; }} |
3. 批处理
测试代码：
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@SpringBootTestclass DemoApplicationTests { @Autowired private SqlSessionFactory sqlSessionFactory; @Test public void testInsertBatch(){ //数据生成 List<Student> studentList = createData(100); //使用批处理 long start = System.currentTimeMillis(); SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH,false); StudentMapper studentMapperNew = sqlSession.getMapper(StudentMapper.class); studentList.stream().forEach(student -> studentMapperNew.insert(student)); sqlSession.commit(); sqlSession.clearCache(); System.out.println(System.currentTimeMillis() - start); } private List<Student> createData(int size){ List<Student> studentList = new ArrayList<>(); Student student; for(int i = 0; i < size; i++){ student = new Student(); student.setName("小王" + i); student.setAge(18); student.setClassId(1); student.setPhone("1585xxxx669"); student.setAddress("未知"); studentList.add(student); } return studentList; }} |
三种方式的对比
MySQL服务器版本：5.6.4
其他依赖版本如下：
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<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.4.4</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.buhe</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.41</version> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.1</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> </resource> </resources> </build></project> |
三种插入方式在不同数据量下的表现，测试结果：
| 插入方式 | 10条 | 100条 | 500条 | 1000条 |
|---|---|---|---|---|
| 循环插入 | 496ms | 3330ms | 15584ms | 33755ms |
| foreach标签 | 268ms | 366ms | 392ms | 684ms |
| 批处理 | 222ms | 244ms | 364ms | 426ms |
三种方式中，批处理的方式效率是最高的，尤其是在数据量大的情况下尤为明显。
其次是foreach标签，foreach标签是通过拼接SQL语句的方式完成批量操作的。但是当拼接的SQL过多，导致SQL大小超过了MySQL服务器中max_allowed_packet变量的值时，会导致操作失败，抛出PacketTooBigException异常。
最后是循环插入的方式，这种方式在数据量小的时候可以使用，在数据量大的情况下效率要低很多。
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1. isnull(expr)
如果expr为null，则返回1，否则返回0
SELECT ISNULL(null) from dual; --结果为1
SELECT isnull(1/0) from dual; --结果为1
SELECT isnull(1/null) from dual; --结果为1
SELECT ISNULL(5) from dual; --结果为0
SELECT ISNULL('a') from dual; --结果为0
SELECT ISNULL(5+5) from dual; --结果为0
2. ifnull(expr1, expr2)
根isnull类似，expr1不为null的情况下，返回expr1，返回expr2
SELECT IFNULL(1,2) from dual; --1
SELECT IFNULL(null,2) from dual; --2
SELECT IFNULL(1/0,'can not be null') from dual; --'can not be null'
3. nullif(expr1, expr2)
nullif和ifnull完全不同，它表示如果两个表达式相同，则返回null，否则返回expr1的值
个人感觉应该叫null if equals
SELECT NULLIF(1,3) from dual; --1
SELECT NULLIF(3,3) from dual; --null
SELECT NULLIF(1+2,3) from dual; --null
4. coalesce(expr1, expr2,… exprN)
发音是core or less，英文的意思是联合/合并，在mysql中的用途是返回第一个不是null的值
SELECT COALESCE(null,1/0,2) from dual; --2
SELECT COALESCE(null,1/0,2,3) from dual; --2
只有两个参数的情况下，相当于ifnull
SELECT IFNULL(null,2) from dual; --2
SELECT COALESCE(null,2) from dual; --2
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