?EntityWrapper是個很強大的玩意，支持多條件查詢
?EntityWrapper<CompanyInfoEntity>() wrapper= new EntityWrapper<CompanyInfoEntity>();
?wrapper.between(column, val1, val2)
?wrapper.groupBy(columns) ?//對應sql中分組
?wrapper.eq(column, params) //相當于where條件
?wrapper.in(column, value) //sql中in
?wrapper.notIn(column, value) //sql中 not in
?wrapper.orderBy(columns, isAsc) //排序
?wrapper.exists(value) //相對于sql中exists查詢
?wrapper.notExists(value) //相當于sql中not exists查詢
?wrapper.notBetween(column, val1, val2) //相當于sql中在某個范圍內使用的between
?wrapper.ge(column, params) //大于等于
?wrapper.le(column, params) //小于等于
?wrapper.like(column, value) //模糊查詢
?wrapper.having(sqlHaving, params) //條件過濾

如下進行倒序案例

使用.orderBy("create_time",false)就可以實現倒序排列查詢

?@Override
? ? public PageUtils queryPage(Map<String, Object> params) {
? ? ? ? //EntityWrapper 可以封裝bean參數
? ? ? ? String name=(String)params.get("name");
? ? ? ? Page<CompanyInfoEntity> page = this.selectPage(
? ? ? ? ? ? ? ? new Query<CompanyInfoEntity>(params).getPage(),
? ? ? ? ? ? ? ? new EntityWrapper<CompanyInfoEntity>()
? ? ? ? ? ? ? ? ? ? ? ? .like(StringUtils.isNotBlank(name),"name", name)//根據公司名進行查詢
? ? ? ? ? ? ? ? ? ? ? ? .orderBy("create_time",false)//按創(chuàng)建時間進行倒序查詢
? ? ? ? );
?
? ? ? ? return new PageUtils(page);
? ? }

根據上面的可以進行很多條件查詢，有興趣的可以自己試一試哦

條件構造器EntityWrapper用法

EntityWrapper 簡介

1、 MybatisPlus 通過 EntityWrapper（簡稱 EW，MybatisPlus 封裝的一個查詢條件構造器）或者 Condition（與 EW 類似）來讓用戶自由的構建查詢條件，簡單便捷，沒有額外的負擔，能夠有效提高開發(fā)效率。

2、實體包裝器，主要用于處理 sql 拼接，排序，實體參數查詢等。

3、注意: 使用的是數據庫字段，不是 Java 屬性。

4、條件參數說明

測試查詢：

@Test
public void testEntityWrapperSelect() {
?? ?//我們需要分頁查詢tbl_employee表中，年齡在18~50之間且性別為男且姓名為Tom的所有用戶
?? ?List<Employee> emps =employeeMapper.selectPage(new Page<Employee>(1, 2),
?? ??? ??? ??? ?new EntityWrapper<Employee>()
?? ??? ??? ??? ?.between("age", 18, 50)
?? ??? ??? ??? ?.eq("gender", 1)
?? ??? ??? ??? ?.eq("last_name", "Tom")
?? ??? ??? ?);
?? ?System.out.println(emps);
?? ?
?? ?//我們需要分頁查詢tbl_employee表中，年齡在18~50之間且性別為男且姓名為Tom的所有用戶
?? ?List<Employee > emps3 = employeeMapper.selectPage(
?? ??? ??? ??? ??? ?new Page<Employee>(1,2),
?? ??? ??? ??? ??? ??? ?Condition.create()
?? ??? ??? ??? ??? ??? ?.between("age", 18, 50)
?? ??? ??? ??? ??? ??? ?.eq("gender", "1")
?? ??? ??? ??? ??? ??? ?.eq("last_name", "Tom")
?? ??? ??? ??? ??? ??? ?);
?? ?System.out.println(emps3);
?? ??? ?
?? ?// 查詢tbl_employee表中， 性別為女并且名字中帶有"老師" 或者 ?郵箱中帶有"a"
?? ?List<Employee> emps1 = employeeMapper.selectList(
?? ??? ??? ?new EntityWrapper<Employee>()
?? ??? ??? ?.eq("gender", 0)
?? ??? ??? ?.like("last_name", "老師")
?? ??? ??? ?//.or() ? ?// SQL: (gender = ? AND last_name LIKE ? OR email LIKE ?)
?? ??? ??? ?.orNew() ? // SQL: (gender = ? AND last_name LIKE ?) OR (email LIKE ?)
?? ??? ??? ?.like("email", "a")
?? ??? ??? ?);
?? ?System.out.println(emps1);
?? ?//查詢性別為女的, 根據age進行排序(asc/desc), 簡單分頁
?? ?List<Employee> emps2 ?= employeeMapper.selectList(
?? ??? ??? ?new EntityWrapper<Employee>()
?? ??? ??? ?.eq("gender", 0)
?? ??? ??? ?.orderBy("age") //默認是升序
?? ??? ??? ?//.orderDesc(Arrays.asList(new String [] {"age"}))
?? ??? ??? ?.last("desc limit 1,3") //在sql最后拼接
?? ??? ??? ?);
?? ?System.out.println(emps2);
}

控制臺輸出：

selectPage方法：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (age BETWEEN ? AND ? AND gender = ? AND last_name = ?)
Parameters: 18(Integer), 50(Integer), 1(Integer), Tom(String)
Total: 1
[Employee [id=1, lastName=Tom, email=tom@atguigu.com, gender=1, age=22]]
selectPage使用Condition：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (age BETWEEN ? AND ? AND gender = ? AND last_name = ?)
Parameters: 18(Integer), 50(Integer), 1(String), Tom(String)
Total: 1
[Employee [id=1, lastName=Tom, email=tom@atguigu.com, gender=1, age=22]]
selectList使用or：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (gender = ? AND last_name LIKE ? OR email LIKE ?)
Parameters: 0(Integer), %老師%(String), %a%(String)
Total: 3
[Employee [id=1, lastName=Tom, email=tom@atguigu.com, gender=1, age=22], Employee [id=2, lastName=Jerry, email=jerry@atguigu.com, gender=0, age=25], Employee [id=7, lastName=王五, email=xz@sina.com, gender=0, age=null]]
selectList使用orNew：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (gender = ? AND last_name LIKE ?) OR (email LIKE ?)
Parameters: 0(Integer), %老師%(String), %a%(String)
Total: 3
[Employee [id=1, lastName=Tom, email=tom@atguigu.com, gender=1, age=22], Employee [id=2, lastName=Jerry, email=jerry@atguigu.com, gender=0, age=25], Employee [id=7, lastName=王五, email=xz@sina.com, gender=0, age=null]]
selectList使用orderBy：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (gender = ?) ORDER BY age
Parameters: 0(Integer)
Total: 2
[Employee [id=7, lastName=王五, email=xz@sina.com, gender=0, age=null], Employee [id=2, lastName=Jerry, email=jerry@atguigu.com, gender=0, age=25]]
selectList使用orderDesc：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (gender = ?) ORDER BY age DESC
Parameters: 0(Integer)
Total: 2
[Employee [id=2, lastName=Jerry, email=jerry@atguigu.com, gender=0, age=25], Employee [id=7, lastName=王五, email=xz@sina.com, gender=0, age=null]]
selectList使用last：
Preparing: SELECT id AS id,last_name AS lastName,email,gender,age FROM tbl_employee WHERE (gender = ?) ORDER BY age desc limit 1,3
Parameters: 0(Integer)
Total: 1
[Employee [id=7, lastName=王五, email=xz@sina.com, gender=0, age=null]]

測試修改：

@Test
public void testEntityWrapperUpdate() {
?? ?Employee employee = new Employee();
?? ?employee.setLastName("王五");
?? ?employee.setEmail("cls@sina.com");
?? ?employee.setGender(0);
?? ?employeeMapper.update(employee,
?? ??? ??? ??? ?new EntityWrapper<Employee>()
?? ??? ??? ??? ?.eq("last_name", "Tom")
?? ??? ??? ??? ?.eq("age", 44)
?? ??? ??? ??? ?);
}

控制臺輸出：

Preparing: UPDATE tbl_employee SET last_name=?, email=?, gender=? WHERE (last_name = ? AND age = ?)
Parameters: 王五(String), cls@sina.com(String), 0(Integer), Tom(String), 44(Integer)
Updates: 0

測試刪除：

@Test
public void testEntityWrapperDelete() {
?? ?employeeMapper.delete(
?? ??? ??? ??? ?new EntityWrapper<Employee>()
?? ??? ??? ??? ?.eq("last_name", "Tom")
?? ??? ??? ??? ?.eq("age", 22)
?? ??? ??? ?);
}

控制臺輸出：