<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.2</version>
    <relativePath/>
</parent>
<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.48</version>
    </dependency>
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    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.4.3</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.9</version>
    </dependency>
</dependencies>

//聲明該實(shí)體類映射的表名
@TableName("t_product")
public class ProductBean {
    //表示該列為主鍵列，value表示該列映射的列名
    //type = IdType.AUTO 表示該列的值使用自動(dòng)增長(zhǎng)列生成
    @TableId(value = "pk_productId",type = IdType.AUTO)
    private Integer id;
    
    //指定當(dāng)前屬性映射的列名
    @TableField("p_name")
    private String name;
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    @TableField("p_createDate")
    private LocalDate createDate;
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    @TableField("p_price")
    private Integer price;
}

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver  #定義配置驅(qū)動(dòng)類
    username: root #mysql登錄用戶名
    password: 123 #mysql登錄密碼
    url: jdbc:mysql://localhost:12345/shopDB?characterEncoding=utf8&allowMultiQueries=true 
    type: com.alibaba.druid.pool.DruidDataSource #配置連接池
    druid:
      one:
        max-active: 100 #最大連接數(shù)
        min-idle: 20 #最小連接數(shù)
        max-wait: 2000 #超時(shí)時(shí)間（ms）
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mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #配置日志
  type-aliases-package: com.project.bean #實(shí)體類所在包，允許用實(shí)體類類名作為別名
  mapper-locations: classpath:*/*Mapper.xml #鏈接 mapper文件

public interface IProductService {
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    public void add(ProductBean productBean);
    public void del(Integer id);
    public void update(Integer id,Integer price);
    public List<ProductBean> findAll();
    public ProductBean findById(Integer id);
    public List<ProductBean> findByItem(String name, 
LocalDate startDate,LocalDate endDate);
}

@Mapper
public interface IProductMapper extends BaseMapper<ProductBean> {
}

@Service
@Transactional//該類所有方法支持事務(wù)
public class ProductServiceImpl implements IProductService {
    @Autowired
    private IProductMapper mapper;
    @Override
    public void add(ProductBean productBean) {
        mapper.insert(productBean);//添加實(shí)體數(shù)據(jù)
    }
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    @Override
    public void del(Integer id) {
        mapper.deleteById(id);//根據(jù)id刪除實(shí)體數(shù)據(jù)
    }
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    @Override
    public void update(Integer id, Integer price) {
        ProductBean productBean = new ProductBean();
        productBean.setId(id);
        productBean.setPrice(price);
        mapper.updateById(productBean);//按id修改實(shí)體屬性
    }
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    @Override
    public List<ProductBean> findAll() {
        return mapper.selectList(null);//查詢所有
    }
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    @Override
    public ProductBean findById(Integer id) {
        return mapper.selectById(id);//按id查詢實(shí)體對(duì)象
    }
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    @Override
    public List<ProductBean> findByItem(String name, 
LocalDate startDate, LocalDate endDate) {
        QueryWrapper<ProductBean> qw = new QueryWrapper<>();//條件集合
        if (name != null && name.length() != 0){
            qw.like("p_name",name);//like 模糊查詢
        }
        if (startDate != null){
            qw.ge("p_creatDate",startDate);//ge 大于等于
        }
        if (endDate != null){
            qw.le("p_createDate",endDate);//le 小于等于
        }
        return mapper.selectList(qw);//按條件查詢
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Main.class)//啟動(dòng)類類模板
public class ProductTest {
    @Autowired
    private IProductService service;
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    @Test
    public void test(){
//        service.add(new ProductBean("999感冒靈", 
LocalDate.parse("2022-06-06"),18));
        System.out.println(service.findAll());
    }
}

@Configuration
public class MyBatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(
                new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
?}

/**
 * 動(dòng)態(tài)條件分頁(yè)查詢
 * @param pageNO 頁(yè)碼
 * @param name 姓名
 * @param startDate 生產(chǎn)起始日期
 * @param endDate 生成結(jié)束日期
 * @return 分頁(yè)對(duì)象
 */
public IPage<ProductBean> findByItem(Integer pageNO, 
String name, LocalDate startDate,LocalDate endDate);

@Mapper
public interface IProductMapper extends BaseMapper<ProductBean> {
}

@Override
public IPage<ProductBean> findByItem(Integer pageNO,
 String name, LocalDate startDate, LocalDate endDate) {
    QueryWrapper<ProductBean> qw = new QueryWrapper<>();
    if (name != null && name.length() != 0){
        qw.like("p_name",name);
    }
    if (startDate != null){
        qw.ge("p_createDate",startDate);
    }
    if (endDate != null){
        qw.le("p_createDate",endDate);
    }
    return mapper.selectPage(new Page(pageNO,3),qw);
}

@RunWith(SpringRunner.class)
@SpringBootTest(classes = PlusMain.class)
public class Test {
    @Autowired
    private IProductService service;
    @org.junit.Test
    public void test(){
//        System.out.println(service.findAll());
        IPage ip = service.findByItem(1,"",null,null);
        System.out.println(ip.getRecords()//得到當(dāng)前數(shù)據(jù)
                +"  "+ip.getTotal()//得到總記錄數(shù)
                +"  "+ip.getPages()//總頁(yè)數(shù)
                +"  "+ip.getCurrent()//得到頁(yè)碼
                +"  "+ip.getSize()//得到每頁(yè)記錄數(shù)
                 );
    }
}

/**
 * 部門實(shí)體類
 */
@TableName("t_dept")
public class DeptBean {
    @TableId(value = "pk_deptId",type = IdType.AUTO)
    private Integer id;
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    @TableField("d_name")
    private String name;
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    @TableField(exist = false)//標(biāo)識(shí)該屬性沒(méi)有對(duì)應(yīng)的列
    private Integer emNum;
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    @TableField(exist = false)//標(biāo)識(shí)該屬性沒(méi)有對(duì)應(yīng)的列
    private List<EmployeeBean> emList;
}
/**
 * 員工實(shí)體類
 */
@TableName("t_employee")
public class EmployeeBean {
    @TableId(value = "pk_emId",type = IdType.AUTO)
    private Integer id;
    @TableField("e_name")
    private String name;
    @TableField("e_job")
    private String job;
    @TableField("e_birthday")
    private LocalDate birthday;
    @TableField("fk_deptId")
    private Integer deptId;
    @TableField(exist = false)
    private DeptBean dept;
}

/**
*部門業(yè)務(wù)接口
*/
public interface IDeptService {
    /**
     * 查詢所有部門，同時(shí)統(tǒng)計(jì)每個(gè)部門的人數(shù)
     * @return 部門集合
     */
    public List<DeptBean> findAll();
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    /**
     * 級(jí)聯(lián)添加，添加部門，同時(shí)添加該部門的員工集合
     * @param dept 部門對(duì)象
     * @param emList 新員工集合
     */
    public void add(DeptBean dept, List<EmployeeBean> emList);
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    /**
     * 刪除部門，同時(shí)級(jí)聯(lián)刪除部門的員工
     * @param id 部門ID
     */
    public void delCasede(Integer id);
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    /**
     * 刪除部門，同時(shí)將該部門員工外鍵設(shè)置為null
     * @param id 部門ID
     */
    public void delSerNull(Integer id);
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    /**
     * 按id查詢部門，同時(shí)查詢?cè)摬块T中所有的員工
     * @param id 部門id
     * @return 部門對(duì)象
     */
    public DeptBean findById(Integer id);
}



/**
 * 員工業(yè)務(wù)接口
 */
public interface IEmployeeService {
    /**
     * 添加員工
     * @param employee 員工對(duì)象
     */
    public void add(EmployeeBean employee);
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    /**
     * 動(dòng)態(tài)條件分頁(yè)查詢，同時(shí)查詢每個(gè)員工所在部門的名稱
     * @param pageNO 頁(yè)碼
     * @param deptName 部門名稱
     * @param name 員工姓名
     * @return 分頁(yè)對(duì)象
     */
    public IPage<EmployeeBean> findByItem(Integer pageNO,
String deptName,String name);
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    /**
     * 按id查詢員工，同時(shí)查詢員工的部門信息
     * @param id 員工編號(hào)
     * @return 員工對(duì)象33
     */
    public EmployeeBean findById(Integer id);
}

/**
*部門 mapper 接口
*/
@Mapper
public interface IDeptMapper extends BaseMapper<DeptBean> {
    @Select("SELECT d.*,COUNT(e.`pk_emId`) emNum FROM t_dept d LEFT JOIN
 t_employee e ON d.`pk_deptId`=e.`fk_deptId`\n" +
            "GROUP BY d.`pk_deptId`")
    @ResultMap("deptMap")
    public List<DeptBean> findAll();
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    @Delete("delete from t_employee where fk_deptId=#{id};" +
            "delete from t_dept where pk_deptId=#{id};")
    public void delCasede(Integer id);
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    @Delete("update t_employee set fk_deptId=null where fk_deptId=#{id};" +
            "delete from t_dept where pk_deptId=#{id};")
    public void delSetNull(Integer id);
}
/**
*員工 mapper 接口
*/
@Mapper
public interface IEmployeeMapper extends BaseMapper<EmployeeBean> {
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    public void addMore(@Param("deptId") Integer deptId,
@Param("emList") List<EmployeeBean> emList);
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    public IPage<EmployeeBean> findByItem(Page pageNO,
@Param("deptName") String deptName,@Param("name") String name);
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}

<mapper namespace="com.project.mapper.IDeptMapper">
    <resultMap id="deptMap" type="DeptBean">
        <id property="id" column="pk_deptId"></id>
        <result property="name" column="d_name"></result>
        <result property="emNum" column="emNum"></result>
    </resultMap>
</mapper>

<mapper namespace="com.project.mapper.IEmployeeMapper">
    <insert id="addMore">
        insert into t_employee (e_name,e_job,e_birthday,fk_deptId)
 values
        <foreach collection="emList" item="em" separator=",">
            (#{em.name},#{em.job},#{em.birthday},#{deptId})
        </foreach>
    </insert>
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    <resultMap id="emMap" type="EmployeeBean">
        <id column="pk_emId" property="id"></id>
        <result column="e_name" property="name"></result>
        <result column="e_job" property="job"></result>
        <result column="e_birthday" property="birthday"></result>
        <result column="d_name" property="dept.name"></result>
    </resultMap>
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    <select id="findByItem" resultMap="emMap">
        select e.*,d.d_name from t_dept d,t_employee e where
 d.pk_deptId=e.fk_deptId
        <if test="deptName != null and deptName != '' ">
            and d_name like "%"#{deptName}"%"
        </if>
        <if test="name != null and name != '' ">
            and e_name like "%"#{name}"%"
        </if>
    </select>
</mapper>

/**
 * 部門業(yè)務(wù)方法
 */
@Service
@Transactional
public class DeptServiceImpl implements IDeptService {
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    @Autowired
    private IDeptMapper deptMapper;
    @Autowired
    private IEmployeeMapper employeeMapper;
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    @Override
    public List<DeptBean> findAll() {
        return deptMapper.findAll();
    }
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    @Override
    public void add(DeptBean dept, List<EmployeeBean> emList) {
        deptMapper.insert(dept);
        employeeMapper.addMore(dept.getId(),emList);
    }
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    @Override
    public void delCasede(Integer id) {
        deptMapper.delCasede(id);
    }
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    @Override
    public void delSerNull(Integer id) {
        deptMapper.delSetNull(id);
    }
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    @Override
    public DeptBean findById(Integer id) {
        DeptBean dept = deptMapper.selectById(id);
        QueryWrapper<EmployeeBean> qw = new QueryWrapper<>();
        qw.eq("fk_deptId",id);
        dept.setEmList(employeeMapper.selectList(qw));
        return dept;
    }
}
/**
 * 員工業(yè)務(wù)方法
 */
@Service
@Transactional
public class EmployeeServiceImpl implements IEmployeeService {
    @Autowired
    IEmployeeMapper employeeMapper;
    @Autowired
    IDeptMapper deptMapper;
    @Override
    public void add(EmployeeBean employee) {
        employeeMapper.insert(employee);
    }
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    @Override
    public IPage<EmployeeBean> findByItem(Integer pageNO, 
String deptName, String name) {
        return employeeMapper.findByItem(new Page(pageNO,3),deptName,name);
    }
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    @Override
    public EmployeeBean findById(Integer id) {
        EmployeeBean em = employeeMapper.selectById(id);
        em.setDept(deptMapper.selectById(em.getDeptId()));
  ··      return em;
    }
}

QueryWrapper<StudentBean> qw = new QueryWrapper<>();
qw.eq("fk.classId",classId);
Integer num = studentMapper.selectCount(qw);