MybatisPlus的通用 CRUD

@Test
public void testInsert(){
    //初始化Employee对象
    Employee employee  = new Employee();
    employee.setLastName("shuchegnxi");
    employee.setEmail("shuchegnxi@atguigu.com");
    //insert 方法在插入时，会根据实体类的每个属性进行非空判断,只有非空属性对应的字段才会出现到sql语句中
    employeeMapper.insert(employee);

    //insertAllColumn方法在插入时，无论属性是否为空，属性所对应的字段都会出现到sql语句中
    //employeeMapper.insertAllColumn(employee);

    //获取当前数据在数据库中的主键值
    System.out.println("主键值："+employee.getId());
}

/*
   @TableId:
    value : 指定表中主键列的列名，如果实体的属性和列名一直，则可以省略不指定
    type: 指定主键的策略

 */
@TableId(value = "id",type = IdType.AUTO)

// 指定该实体对应的数据库的表名
@TableName(value = "tbl_employee")

<bean id="sqlSessionFactoryBean" class="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean">
   <!-- 数据源 -->
   <property name="dataSource" ref="dataSource"></property>
   <property name="configLocation" value="classpath:mybatis.xml"></property>
   <!-- 别名处理 -->
   <property name="typeAliasesPackage" value="com.atguigu.mp.beans"></property>      
   
   <!-- 注入全局MP策略配置 -->
   <property name="globalConfig" ref="globalConfiguration"></property>
</bean>

<!-- 定义MybatisPlus的全局策略配置-->
<bean id ="globalConfiguration" class="com.baomidou.mybatisplus.entity.GlobalConfiguration">
   <!-- 在2.3版本以后，dbColumnUnderline 默认值就是true -->
   <property name="dbColumnUnderline" value="true"></property>
   
   <!-- 全局的主键策略 -->
   <property name="idType" value="0"></property>
   
   <!-- 全局的表前缀策略配置 -->
   <property name="tablePrefix" value="tbl_"></property>
   
</bean>

@TableField(value = "last_name")
private String lastName;

@TableField(exist = false)

//insert 方法在插入时，会根据实体类的每个属性进行非空判断,只有非空属性对应的字段才会出现到sql语句中
employeeMapper.insert(employee);

//insertAllColumn方法在插入时，无论属性是否为空，属性所对应的字段都会出现到sql语句中
employeeMapper.insertAllColumn(employee);

@Test
public void testUpdate(){
    Employee employee  = new Employee();
    employee.setId(9);
    employee.setLastName("houchen");
    employee.setEmail("houchen@qq.com");
    employee.setGender(2);
    //返回结果是 对当前数据库影响的行数
    // 
    Integer result = employeeMapper.updateById(employee);
    System.out.println(result);
}

//通过id查询
Employee employee = employeeMapper.selectById(9);
System.out.println(employee);

//通过多个列进行查询
Employee emp  = new Employee();
emp.setLastName("houchen");
emp.setEmail("houchen@qq.com");
Employee employee1 = employeeMapper.selectOne(emp);
System.out.println(employee1);

// 通过多个id进行查询
List<Employee> employees = employeeMapper.selectBatchIds(Arrays.asList(1, 2, 3));
for(Employee e:employees){
    System.out.println(e);
}

//selectByMap
HashMap<String, Object> columnMap = new HashMap<>();
//key 是表中的列名
columnMap.put("last_name", "houchen");
List<Employee> employees = employeeMapper.selectByMap(columnMap);
for(Employee e:employees){
    System.out.println(e);
}

//分页查询 selectPage
List<Employee> employees = employeeMapper.selectPage(new Page<>(2, 2), null);
for(Employee e:employees){
    System.out.println(e);
}

@Test
public void testDelete(){
    //根据ID删除数据
    //employeeMapper.deleteById(9);

    //根据条件删除数据
    HashMap<String, Object> columnMap = new HashMap<>();
    //key 是表中的列名
    columnMap.put("last_name", "MP");
    employeeMapper.deleteByMap(columnMap);

    // 批量删除deleteBatchIds
    employeeMapper.deleteBatchIds(Arrays.asList(1,2));
}