老司机学习MyBatis之动态SQL使用foreach在MySQL中批量插入

一、前言

当我们使用MyBatis一次性插入多条数据时候也可以使用foreach标签，本文我们将介绍MySQL中使用MyBatis批量插入数据的两种方式。

二、案例

①第一种方式

修改EmpMapper文件，增加batchSave方法

/**
* 批量插入数据
* @param empList
*/
public void batchSave(List<Emp> empList);

修改EmpMapper.xml文件

<insert id="batchSave">
	into t_emp(emp_name,emp_email,dept_id) VALUES 
	<foreach collection="list" item="emp" separator=",">
		(#{emp.empName}, #{emp.empEmail}, #{emp.deptId})
	</foreach>
</insert>

修改MyBatis测试类，增加测试方法testBatchSave

@Test
public void testBatchSave() throws IOException {
	SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
	SqlSession openSession = sqlSessionFactory.openSession();
	try {
		EmpMapper mapper = openSession.getMapper(EmpMapper.class);
		List<Emp> empList = new ArrayList<Emp>();
		empList.add(new Emp(null,"Lucy","[email protected]",1));
		empList.add(new Emp(null,"Lily","[email protected]",2));
		empList.add(new Emp(null,"Lizy","[email protected]",3));
		mapper.batchSave(empList);
		//别忘了事务最后要提交
		openSession.commit();
	} finally {
		openSession.close();
	}
}

测试控制台打印结果如下

2017-08-13 12:47:42,489 [main] [com.queen.mybatis.mapper.EmpMapper.batchSave]-[DEBUG] ==>  Preparing: insert into t_emp(emp_name,emp_email,dept_id) VALUES (?, ?, ?) , (?, ?, ?) , (?, ?, ?) 
2017-08-13 12:47:42,547 [main] [com.queen.mybatis.mapper.EmpMapper.batchSave]-[DEBUG] ==> Parameters: Lucy(String), [email protected](String), 1(Integer), Lily(String), [email protected](String), 2(Integer), Lizy(String), [email protected](String), 3(Integer)
2017-08-13 12:47:42,549 [main] [com.queen.mybatis.mapper.EmpMapper.batchSave]-[DEBUG] <==    Updates: 3

由上面打印SQL可知，MySQL支持 insert into table values(?,?,?),(?,?,?) 这种语法

②第二种方式

修改EmpMapper.xml文件

测试控制台打印结果报错

org.apache.ibatis.exceptions.PersistenceException: 
### Error updating database.  Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'insert into t_emp(emp_name,emp_email,dept_id) VALUES 
				('Lily123', 'Lily123@s' at line 4
### The error may involve defaultParameterMap
### The error occurred while setting parameters
### SQL: insert into t_emp(emp_name,emp_email,dept_id) VALUES      (?, ?, ?)    ;     insert into t_emp(emp_name,emp_email,dept_id) VALUES      (?, ?, ?)    ;     insert into t_emp(emp_name,emp_email,dept_id) VALUES      (?, ?, ?)
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'insert into t_emp(emp_name,emp_email,dept_id) VALUES 
				('Lily123', 'Lily123@s' at line 4

报错信息说：不支持这种一次性插入多条的语法，这时候我们要怎么处理？

这里，需要修改mysql的连接参数allowMultiQueries=true

再次测试一下，成功。这种方式也适合于其他的批量操作，例如更新，删除；

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