MyBatis：MyBatis-Plus條件構造器EntityWrapper

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， 能夠有效提高開發效率。
• 2、實體包裝器，主要用於處理 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:

 

 

查詢測試

@Test
public void testEntityWrapperSelect() {


1.    //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);
    

2.    //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);
        


3.    // 查詢tbl_employee表中， 性別為女並且名字中帶有"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);



4.    //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);
}

日志輸出：

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=[e-mail], 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=[e-mail], 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=[e-mail], gender=1, age=22], Employee [id=2, lastName=Jerry, email=[e-mail], gender=0, age=25], Employee [id=7, lastName=王五, email=[e-mail], 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=[e-mail], gender=1, age=22], Employee [id=2, lastName=Jerry, email=[e-mail], gender=0, age=25], Employee [id=7, lastName=王五, email=[e-mail], 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=[e-mail], gender=0, age=null], Employee [id=2, lastName=Jerry, email=[e-mail], 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=[e-mail], gender=0, age=25], Employee [id=7, lastName=王五, email=[e-mail], 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=[e-mail], gender=0, age=null]]

修改測試

@Test
public void testEntityWrapperUpdate() {
    Employee employee = new Employee();
    employee.setLastName("王五");
    employee.setEmail("[e-mail]");
    employee.setGender(0);
    employeeMapper.update(employee,
                new EntityWrapper<Employee>()
                .eq("last_name", "Tom")
                .eq("age", 44)
                );
}

日志輸出：

Preparing: UPDATE tbl_employee SET last_name=?, email=?, gender=? WHERE (last_name = ? AND age = ?) 
Parameters: 王五(String), [e-mail](String), 0(Integer), Tom(String), 44(Integer)  
Updates: 0

刪除測試

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

日志輸出：

Preparing: DELETE FROM tbl_employee WHERE (last_name = ? AND age = ?)   
Parameters: Tom(String), 22(Integer)
Updates: 1

 

文章轉載至：https://blog.csdn.net/lizhiqiang1217/article/details/89738906