How does MyBatis execute multiple update statements?

MyBatis offers two ways to execute multiple update statements: by using the `` tag or by using batch operations.

1. Utilizing the tag.

The tag in MyBatis is used to iterate over collections and perform repetitive operations. It can be utilized to execute multiple update statements.

<update id="batchUpdate" parameterType="java.util.List">
  <foreach collection="list" item="item" index="index" open="" close="" separator=";">
    UPDATE your_table SET column1 = #{item.column1}, column2 = #{item.column2}
    WHERE id = #{item.id}
  </foreach>
</update>

In the example above, the `` tag iterates through a List containing updated data and executes the update statement for each item.

Afterwards, in your Java code, you can invoke the update statement and pass a List containing the data that needs to be updated.

2. Use batch operation

MyBatis also offers a more efficient way to execute multiple update statements, known as batch processing. Batch processing utilizes the database’s batch processing functionality to send multiple statements together for execution, reducing communication overhead.

SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH);
YourMapper mapper = sqlSession.getMapper(YourMapper.class);
List<YourData> dataList = new ArrayList<>();
// 添加需要更新的数据到dataList
for (YourData data : dataList) {
  mapper.update(data);
}
sqlSession.commit();
sqlSession.close();

In the example above, first a `SqlSession` using batch operations is created. Then, by obtaining the corresponding Mapper object, the `update` method can be called to execute each update statement. Finally, before committing the transaction and closing the `SqlSession`, the `commit` method must be called.

Please make sure to enable batch processing when configuring MyBatis and optimize accordingly based on the database type.