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Mybatis Plus的删除操作内置了4种方法，我们来演示一下Mybatis Plus的删除操作。 
Mybatis Plus mapper的删除操作 1、根据主键ID删除指定单条数据 方法： int deleteById(Serializable id);代码： @Test public void testDeleteById() { System.out.println(("----- deleteById method test ------")); List userList = userMapper.selectList(null); System.out.println("-----删除前数据:"); userList.forEach(System.out::println); userMapper.deleteById(5L); System.out.println("-----删除后剩余数据:"); List userList2 = userMapper.selectList(null); userList2.forEach(System.out::println); }前面已经输出了较多sql，我们这里简洁一些，只输出打印的数据 -----删除前数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=3, name=Tom, age=28, [email protected])User(id=4, name=Sandy, age=21, [email protected])User(id=5, name=Billie, age=24, [email protected])-----删除后剩余数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=3, name=Tom, age=28, [email protected])User(id=4, name=Sandy, age=21, [email protected])2、基于map中设置的key-value，删除一条或多条数据 基于map的删除，可以设置多个列作为条件，被匹配的数据都将被删除。 方法： int deleteByMap(@Param(Constants.COLUMN_MAP) Map columnMap);代码： @Test public void testDeleteByMap() { System.out.println(("----- deleteByMap method test ------")); List userList = userMapper.selectList(null); System.out.println("-----删除前数据:"); userList.forEach(System.out::println); Map columnMap = new HashMap(); columnMap.put("Name","Tom"); userMapper.deleteByMap(columnMap); System.out.println("-----删除后剩余数据:"); List userList2 = userMapper.selectList(null); userList2.forEach(System.out::println); }输出： -----删除前数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=3, name=Tom, age=28, [email protected])User(id=4, name=Sandy, age=21, [email protected])User(id=5, name=Billie, age=24, [email protected])-----删除后剩余数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=4, name=Sandy, age=21, [email protected])User(id=5, name=Billie, age=24, [email protected])3、基于一个实体作为条件，删除一条或多条数据 方法： int delete(@Param(Constants.WRAPPER) Wrapper wrapper);如果方法的参数设置为null，那么相当于全表删除 代码： 输出结果： -----删除前数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=3, name=Tom, age=28, [email protected])User(id=4, name=Sandy, age=21, [email protected])User(id=5, name=Billie, age=24, [email protected])==> Preparing: DELETE FROM user ==> Parameters: Preparing: SELECT id,name,age,email FROM user ==> Parameters: Preparing: DELETE FROM user ==> Parameters: idList);代码： @Test public void testDeleteBatchIds() { System.out.println(("----- deleteBatchIds method test ------")); List userList = userMapper.selectList(null); System.out.println("-----删除前数据:"); userList.forEach(System.out::println); List list = new ArrayList(); list.add(4L); list.add(5L); userMapper.deleteBatchIds(list); System.out.println("-----删除后剩余数据:"); List userList2 = userMapper.selectList(null); userList2.forEach(System.out::println); }输出： -----删除前数据:User(id=1, name=Jone, age=18, [email protected])User(id=2, name=Jack, age=20, [email protected])User(id=3, name=Tom, age=28, [email protected])User(id=4, name=Sandy, age=21, [email protected])User(id=5, name=Billie, age=24, [email protected])==> Preparing: DELETE FROM user WHERE id IN ( ? , ? ) ==> Parameters: 4(Long), 5(Long) Preparing: SELECT id,name,age,email FROM user ==> Parameters: |
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