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指定數(shù)據(jù)庫(kù)表名注解：@TableName

MP默認(rèn)主鍵名是id

指定表的主鍵注解：@TableId

實(shí)體屬性名和表中字段名對(duì)應(yīng)注解：@TableField("")

selct排除字段

/**

?* @date 2020年2月23日??

?* @author 翁?hào)|州

?* @所有方法的代碼點(diǎn)擊查看全文，整理了一整天累死了

?*/

package first;

import java.time.LocalDateTime;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.junit.Assert;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

import org.springframework.test.context.junit4.SpringRunner;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;

import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;

import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;

import com.baomidou.mybatisplus.core.metadata.IPage;

import com.baomidou.mybatisplus.core.toolkit.StringUtils;

import com.baomidou.mybatisplus.core.toolkit.Wrappers;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

import com.baomidou.mybatisplus.extension.service.additional.query.impl.LambdaQueryChainWrapper;

import com.baomidou.mybatisplus.extension.service.additional.update.impl.LambdaUpdateChainWrapper;

import com.mp.dao.UserMapper;

import com.mp.entity.User;

import com.mp.service.UserService;

/**

?* @date 2020年2月23日??

?* @author 翁?hào)|州

?* @方法中文名稱:

?*/

@RunWith(SpringRunner.class)

@SpringBootTest

public class SimpleTest {

@Autowired

private UserMapper userMapper;

//展示所有

@Test

public void select() {

List<User> list = userMapper.selectList(null);

Assert.assertEquals(5, list.size());

list.forEach(System.out::println);

System.out.println();

}

//傳統(tǒng)添加

public void insert() {

User user = new User();

user.setName("名字");

user.setAge(31);

user.setManagerId(123L);

user.setCreateTime(LocalDateTime.now());

int rows = userMapper.insert(user);

System.out.println("影響記錄數(shù)"+rows);

}

//單體展示

public void selectById() {

User user = userMapper.selectById(123L);

System.out.println(user);

}

//多條展示

public void selectByIds() {

List<Long> idList = Arrays.asList(123L,234L,345L);

List<User> users = userMapper.selectBatchIds(idList);

users.forEach(System.out::println);

}

//map形式查詢

public void selectByMap() {

Map<String, Object> columnMap = new HashMap<>();

columnMap.put("name", "王天風(fēng)");

columnMap.put("age", 25);

List<User> users = userMapper.selectByMap(columnMap);

users.forEach(System.out::println);

}

//wrapper 名字包含雨且年齡小于40

public void selectByWrapper() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.eq("name", "雨").lt("age", 40);

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//wrapper 名字包含雨，且年齡在20到40之間,email不為空

public void selectByWrapper2() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.eq("name", "雨").between("age", 20, 40).isNotNull("email");

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//wrapper 名字包含王，年齡大于等于25，按年齡降序排序，而后再按id升序排序

public void selectByWrapper3() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.likeRight("name", "王").or().ge("age", 25).orderByDesc("age").orderByAsc("id");

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//創(chuàng)建日期為2019年2月14日且直屬上級(jí)名字為王姓

public void selectByWrapper4() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.apply("date_format(create_time,'%Y-%m-%d')={0}", "2019-02-14 or true or true")

.inSql("manager_id", "select id from user where name like '王%'");

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//名字為王姓，并且(年齡小于40或郵箱不為空)

public void selectByWrapper5() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.likeRight("name", "王").and(wq -> wq.lt("age", 40).or().isNotNull("email"));

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//名字為王姓，或者(年齡小于40并且年齡大于20并且郵箱不為空)

public void selectByWrapper6() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.likeRight("name", "王").or(wq -> wq.between("age", 20, 40).isNotNull("email"));

//queryWrapper.likeRight("name", "王").or(wq -> wq.lt("age", 40).gt("age", 20).isNotNull("email"));

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//名字為王姓，并且(年齡小于40或郵箱不為空)

public void selectByWrapper7() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.nested(wq -> wq.lt("age", 40).or().isNotNull("email")).likeRight("name", "王");

//queryWrapper.likeRight("name", "王").and(wq -> wq.lt("age", 40).or().isNotNull("email"));

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//年齡為30，31，34，35

public void selectByWrapper8() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.in("age", Arrays.asList(30,31,34,35));

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//只返回滿足條件的其中一條語(yǔ)句即可

public void selectByWrapper9() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.in("age", Arrays.asList(30,31,34,35)).last("limit 1");

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//名字中包含雨并且年齡小于40,只展示id和名字

public void selectByWrapperSupper() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.select("id","name").like("name", "雨").lt("age", 40);

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//名字中包含雨并且年齡小于40,展示不包括創(chuàng)建字段和上級(jí)id字段的其他字段

public void selectByWrapperSupper2() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.like("name", "雨").lt("age", 40)

.select(User.class, info -> !info.getColumn().equals("create_time")

&&!info.getColumn().equals("manager_id"));

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//測(cè)試condition

@Test

public void testCondition() {?

String name = "王";

String email = "";

condition1(name,email);

}

//名字中包含王,當(dāng)email為空時(shí)不查詢

public void condition1(String name,String email) {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

//傳統(tǒng)方法

//if (StringUtils.isNotColumnName(name)) {

// queryWrapper.like("name", name);

//}

//if (StringUtils.isNotColumnName(email)) {

// queryWrapper.like("email", email);

//}

queryWrapper.like(StringUtils.isNotEmpty(name), "name",name)

.like(StringUtils.isNotEmpty(email), "email",email);

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//查找姓名為劉紅雨且年齡32歲的數(shù)據(jù)

public void selectByWrapperEntity() {?

User whereUser = new User();

whereUser.setName("劉紅雨");

whereUser.setAge(32);

QueryWrapper<User> queryWrapper = new QueryWrapper<User>(whereUser);

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//allEq

public void selectByWrapperAllEq() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

Map<String, Object> params = new HashMap<String, Object>();

//姓名為王天風(fēng),年齡25

//params.put("name", "王天風(fēng)");

//params.put("age", 25);

//queryWrapper.allEq(params);

//姓名為王天風(fēng),年齡為空則忽略

params.put("name", "王天風(fēng)");

params.put("age", null);

//queryWrapper.allEq(params,false);

//剔除name查詢條件

queryWrapper.allEq((k,v)->!k.equals("name"), params);

List<User> userList = userMapper.selectList(queryWrapper);

userList.forEach(System.out::println);

}

//Map格式,查詢姓名包含雨，年齡小于40的數(shù)據(jù)

public void selectByWrapperMaps() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.like("name", "雨").lt("age", 40);

List<Map<String, Object>> userList = userMapper.selectMaps(queryWrapper);

userList.forEach(System.out::println);

}

//Map格式,按照直屬上級(jí)id分組，查詢每組的平均年齡，最大年齡，最小年齡，只去年齡總和小于500的組

public void selectByWrapperMaps2() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.select("avg(age) avg_age","min(age) min_age","max(age) max_age")

.groupBy("manager_id").having("sum(age)<{0}",500);

List<Map<String, Object>> userList = userMapper.selectMaps(queryWrapper);

userList.forEach(System.out::println);

}

//obj格式，查詢姓名包含雨，年齡小于40的數(shù)據(jù)

public void selectByWrapperobjs() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.select("id","name").like("name", "雨").lt("age", 40);

List<Object> userList = userMapper.selectObjs(queryWrapper);

userList.forEach(System.out::println);

}

//查詢姓名包含雨，年齡小于40的數(shù)據(jù)條數(shù)的總條數(shù)

public void selectByWrapperCount() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.like("name", "雨").lt("age", 40);

Integer count = userMapper.selectCount(queryWrapper);

System.out.println("總記錄數(shù)"+ count);

}

//查詢姓名包含雨，年齡小于40的數(shù)據(jù)條數(shù)的一條數(shù)據(jù)

public void selectByWrapperOne() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.like("name", "雨").lt("age", 40);

User user = userMapper.selectOne(queryWrapper);

System.out.println(user);

}

//lambda,三種起手

public void selectLambda() {?

//LambdaQueryWrapper<User> lambda = new QueryWrapper<User>().lambda();

//LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<User>();

LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();

lambdaQuery.like(User::getName, "雨").lt(User::getAge, 40);

List<User> userList = userMapper.selectList(lambdaQuery);

userList.forEach(System.out::println);

}

//lambda,名字為王姓，并且(年齡小于40或郵箱不為空)

public void selectLambda2() {?

LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();

lambdaQuery.likeRight(User::getName, "王")

.and(lqw ->lqw.lt(User::getAge, 40).or().isNotNull(User::getEmail));

List<User> userList = userMapper.selectList(lambdaQuery);

userList.forEach(System.out::println);

}

//lambda,名字為王姓，并且(年齡小于40或郵箱不為空)，LambdaQueryChainWrapper一氣呵成

public void selectLambda3() {?

List<User> userList = new LambdaQueryChainWrapper<User>(userMapper).like(User::getName, "雨").ge(User::getAge, 20).list();

userList.forEach(System.out::println);

}

//分頁(yè)

public void selectPage() {?

QueryWrapper<User> queryWrapper = new QueryWrapper<User>();

queryWrapper.ge("age", 26);

Page<User> page = new Page<User>(1,10);//1為第一頁(yè)，10為一頁(yè)10行

IPage<User> iPage = userMapper.selectPage(page, queryWrapper);

System.out.println("總頁(yè)數(shù)"+iPage.getPages());

System.out.println("總記錄數(shù)"+iPage.getTotal());

List<User> userList = iPage.getRecords();

userList.forEach(System.out::println);

}

//傳統(tǒng)根據(jù)id更新,根據(jù)id更新數(shù)據(jù)

public void updateById() {?

User user = new User();

user.setId(123L);

user.setAge(25);

user.setEmail("wtf2@baomidou.com");

int rows = userMapper.updateById(user);

System.out.println("影響記錄數(shù)"+ rows);

}

//傳統(tǒng)根據(jù)Wrapper更新，姓名為李藝偉且年齡為28的數(shù)據(jù)，更改其id，年齡和郵箱

public void updateByWrapper2() {?

UpdateWrapper<User> updateWrapper = new UpdateWrapper<User>();

updateWrapper.eq("name", "李藝偉").eq("age", 28);

User user = new User();

user.setId(123L);

user.setAge(25);

user.setEmail("wtf2@baomidou.com");

int rows = userMapper.update(user,updateWrapper);

System.out.println("影響記錄數(shù)"+ rows);

}

//Wrapper更新，姓名為李藝偉且年齡為29的數(shù)據(jù)，更改年齡為30

public void updateByWrapper3() {?

UpdateWrapper<User> updateWrapper = new UpdateWrapper<User>();

updateWrapper.eq("name", "李藝偉").eq("age", 29).set("age", 30);

int rows = userMapper.update(null,updateWrapper);

System.out.println("影響記錄數(shù)"+ rows);

}

//lambda的Wrapper更新，姓名為李藝偉且年齡為29的數(shù)據(jù)，更改年齡為30

public void updateByWrapperLambda() {?

LambdaUpdateWrapper<User> lambdaUpdate = Wrappers.<User>lambdaUpdate();

lambdaUpdate.eq(User::getName, "李藝偉").eq(User::getAge, 30).set(User::getAge, 31);

int rows = userMapper.update(null,lambdaUpdate);

System.out.println("影響記錄數(shù)"+ rows);

}

//lambda的Wrapper更新，姓名為李藝偉且年齡為29的數(shù)據(jù)，更改年齡為30,一氣呵成

public void updateByWrapperLambdaChain() {?

boolean update = new LambdaUpdateChainWrapper<User>(userMapper)

.eq(User::getName, "李藝偉").eq(User::getAge, 29).set(User::getAge, 31).update();

System.out.println(update);

}

//根據(jù)id刪除數(shù)據(jù)

public void deleteById() {

int rows = userMapper.deleteById(123L);

System.out.println("刪除條數(shù)"+rows);

}

//根據(jù)map中名稱為向后，年齡25刪除數(shù)據(jù)

public void deleteByMap() {

Map<String, Object> columnMap = new HashMap<>();

columnMap.put("name", "向后");

columnMap.put("age",25);

int rows = userMapper.deleteByMap(columnMap);

System.out.println("刪除條數(shù)"+rows);

}

//根據(jù)id刪除多條數(shù)據(jù)

public void deleteByBatchIds() {

int rows = userMapper.deleteBatchIds(Arrays.asList(123L,234L,345L));

System.out.println("刪除條數(shù)"+rows);

}

//根據(jù)wrapper刪除數(shù)據(jù)

public void deleteByWrapper() {

LambdaQueryWrapper<User> lambdaQueryWrapper = Wrappers.<User>lambdaQuery();

lambdaQueryWrapper.eq(User::getAge, 27).or().gt(User::getAge, 41);

int rows = userMapper.delete(lambdaQueryWrapper);

System.out.println("刪除條數(shù)"+rows);

}

//AR模式添加

public void insert2() {

User user = new User();

user.setName("劉華");

user.setAge(29);

user.setEmail("lh@baomidou.com");

user.setManagerId(123L);

user.setCreateTime(LocalDateTime.now());

boolean insert = user.insert();//類繼承Model

System.out.println(insert);

}

//AR模式查找

public void selectById2() {

User user = new User();

user.setId(123L);

User selectById = user.selectById();

System.out.println(selectById);

}

//AR模式更新

public void updateById2() {

User user = new User();

user.setId(123L);

user.setName("劉華");

user.setAge(29);

user.setEmail("lh@baomidou.com");

user.setManagerId(123L);

user.setCreateTime(LocalDateTime.now());

boolean updateById = user.updateById();//類繼承Model

System.out.println(updateById);

}

//AR模式添加或更新

public void insertOrUpdate() {

User user = new User();

user.setName("劉華");

user.setAge(29);

user.setEmail("lh@baomidou.com");

user.setManagerId(123L);

user.setCreateTime(LocalDateTime.now());

boolean insertOrUpdate = user.insertOrUpdate();//類繼承Model

System.out.println(insertOrUpdate);

}

@Autowired

private UserService userService;

//使用service，獲取一條數(shù)據(jù)

public void getOne() {

User one = userService.getOne(Wrappers.<User>lambdaQuery().gt(User::getAge, 25));//多條報(bào)錯(cuò)

System.out.println(one);

}

//使用service，獲取一條數(shù)據(jù)

public void batch() {

User user1 = new User();

user1.setName("徐麗1");

user1.setAge(28);

User user2 = new User();

user2.setId(123L);

user2.setName("徐麗2");

user2.setAge(29);

List<User> users = Arrays.asList(user1,user2);

boolean saveBatch = userService.saveBatch(users);

//保存或更新

//userService.saveOrUpdateBatch(users);

System.out.println(saveBatch);

}

//使用service，lambda查詢年齡大于25且名字包含雨的數(shù)據(jù)，一氣呵成

public void chain1() {

List<User> users = userService.lambdaQuery().gt(User::getAge, 25).like(User::getName, "雨").list();

users.forEach(System.out::println);

}

//使用service，lambda更新年齡為25的數(shù)據(jù)為26，一氣呵成

public void chain2() {

boolean update = userService.lambdaUpdate().eq(User::getAge, 25).set(User::getAge, 26).update();

System.out.println(update);

}

//使用service，lambda刪除年齡為25的數(shù)據(jù)，一氣呵成

public void chain3() {

boolean remove = userService.lambdaUpdate().gt(User::getAge, 25).remove();

System.out.println(remove);

}

}

如果實(shí)體屬性和數(shù)據(jù)庫(kù)字段對(duì)不上:MP提供有三種方式排除非表字段使用方法:

?1.在實(shí)體類使用transient標(biāo)注成員變量,數(shù)據(jù)映射時(shí)就不會(huì)參與序列化

2.要序列化: 設(shè)置該屬性位靜態(tài)變量static

3.在該屬性上面添加@TableFieId(exist=false):exist代表數(shù)據(jù)庫(kù)是否有該字段,false代表沒有

insert():插入數(shù)據(jù)

普通查詢方法：

1、List<T>?selectBatch(List<T> ids)

2、List<T> selectByMap(Map<key,value> map)

PS：map中的key為數(shù)據(jù)庫(kù)中的列名（如果輸入的是實(shí)體類中的屬性名會(huì)報(bào)錯(cuò)）、value是列對(duì)應(yīng)的值

MP 實(shí)體類數(shù)據(jù)庫(kù)字段對(duì)應(yīng)規(guī)則

1、@TableId作用

MP默認(rèn)找實(shí)體類屬性名為id的字段作為主鍵，如果沒找到會(huì)報(bào)錯(cuò)，此時(shí)在實(shí)體類對(duì)應(yīng)主鍵字段上加@TableId注解就可以了

2、其他字段對(duì)應(yīng)規(guī)則

MP默認(rèn)實(shí)體類屬性名（除主鍵外）與數(shù)據(jù)庫(kù)字段名稱對(duì)應(yīng)規(guī)則為 ：

realName -> real_name

3、@TableField("數(shù)據(jù)庫(kù)列名")

private String name；

實(shí)體類屬性名與數(shù)據(jù)庫(kù)列名不一致時(shí)使用此注解

4、@TableField(exist=false)

private String remark;

此注解表明實(shí)體類中的某個(gè)屬性不是數(shù)據(jù)庫(kù)表中字段

MyBatis-Plus特性：

無(wú)侵入，損耗小、強(qiáng)大的CRUD操作

支持Lambda形式調(diào)用、支持多種數(shù)據(jù)庫(kù)

支持主鍵自動(dòng)生成、支持ActiveRecord模式

如果判定isNotEmpty為true,則進(jìn)行該字段的對(duì)比查詢

如果返回false,說(shuō)明這個(gè)字段為空,不進(jìn)行按此字段查詢

select(字段1,字段2) 選擇字段返回,select可以寫在queryWrapper后面:

last(語(yǔ)句)?

last只能在mp中使用一次,多次調(diào)用將以最后一次為準(zhǔn)

年齡在(30,31,34,35)的

使用in

(年齡小于40或郵箱不為空)并且名字為王姓:

nested(wq->wq...)?

nested為嵌套的意思

說(shuō)明age合is not null字段為整體

默認(rèn)實(shí)體中不為null的字段會(huì)出現(xiàn)在set中

這里是更新name equals "李藝偉" 并且 age equals 28 的user數(shù)據(jù)

更新的數(shù)據(jù)為set的 email 和 set的 age

通用mapper的操作中update(操作對(duì)象,wrapper條件)