July 23, 2022 - mapper file description

explain ：

mybatis in xml The document states ：

File header information ：

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       <?xml 
       
       version="1.0" encoding="UTF-8" ?>
       
       

       
       <!DOCTYPE mapper
       
       
        
       
       PUBLIC "-//mybatis.org//DTD Mapper 3.0//en"
       
       
        
       
       "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
      
      
      
      

       
       
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among ：

resultMap The label is ： return map Type of data , It can be configured , That is, you can configure when the attributes in the entity class are inconsistent with the fields in the table in the database , Thus, it is configured as a one-to-one correspondence .

namespace Is the address of the corresponding interface file

select Query the corresponding sql sentence ,id Is the corresponding interface name , It also contains the return value type map and type Something like that , Single and multiple

inseret Add for input

update To modify , Update data

delete To delete

For these , The double label is for sql sentence , Writing xml When you file , If sql The statement is not sure whether it is right , After testing in the database management software , Then put it into the file ...

Code demonstration ：

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       <?xml 
       
       version="1.0" encoding="UTF-8" ?>
       
       

       
       <!DOCTYPE mapper
       
       
        
       
       PUBLIC "-//mybatis.org//DTD Mapper 3.0//en"
       
       
        
       
       "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
       
       

       
       <
       
       mapper 
       
       namespace=
       
       "com.mapper.UserMapper"
       
       >
       
       

       
       
    
       
       <
       
       resultMap 
       
       id=
       
       "userMap" 
       
       type=
       
       "User"
       
       >
       
       
        
       
       <
       
       id 
       
       column=
       
       "id" 
       
       property=
       
       "id" 
       
       />
       
       
        
       
       <
       
       result 
       
       column=
       
       "username" 
       
       property=
       
       "username"  
       
       />
       
       
        
       
       <
       
       result 
       
       column=
       
       "sex" 
       
       property=
       
       "sex"  
       
       />
       
       
        
       
       <
       
       result 
       
       column=
       
       "birthday" 
       
       property=
       
       "birthday"  
       
       />
       
       
        
       
       <
       
       result 
       
       column=
       
       "address" 
       
       property=
       
       "address" 
       
       />
       
       
    
       
       </
       
       resultMap
       
       >
       
       

       
       
    
       
       <
       
       select 
       
       id=
       
       "findAllUser" 
       
       resultMap=
       
       "userMap"
       
       >
       
       
        SELECT * FROM  `user`
       
       
    
       
       </
       
       select
       
       >
       
       

       
       
    
       
       <
       
       select 
       
       id=
       
       "findUserById" 
       
       parameterType=
       
       "int" 
       
       resultMap=
       
       "userMap"
       
       >
       
       
        SELECT * FROM  `user` WHERE  id=#{id}
       
       
    
       
       </
       
       select
       
       >
       
       

       
       
    
       
       <
       
       select 
       
       id=
       
       "findUserByUsernameAndAddress" 
       
       parameterType=
       
       "string" 
       
       resultMap=
       
       "userMap"
       
       >
       
       
        SELECT * FROM `user` WHERE username=#{username} AND address=#{address}
       
       
    
       
       </
       
       select
       
       >
       
       

       
       
    
       
       <
       
       insert 
       
       id=
       
       "addUser" 
       
       parameterType=
       
       "User"
       
       >
       
       
        INSERT  INTO   `user` VALUES (NULL ,#{username},#{sex},#{birthday},#{address})
       
       
    
       
       </
       
       insert
       
       >
       
       
    
       
       <
       
       delete 
       
       id=
       
       "deleteUserById" 
       
       parameterType=
       
       "int"
       
       >
       
       
        DELETE FROM `user` WHERE id=#{id}
       
       
    
       
       </
       
       delete
       
       >
       
       
    
       
       <
       
       delete 
       
       id=
       
       "deleteUserByUsername" 
       
       >
       
       
        DELETE FROM `user` WHERE username=#{username}
       
       
    
       
       </
       
       delete
       
       >
       
       
    
       
       <
       
       update 
       
       id=
       
       "updateUser" 
       
       parameterType=
       
       "User"
       
       >
       
       
        UPDATE `user` SET username=#{username} WHERE id=#{id}
       
       
    
       
       </
       
       update
       
       >
       
       

       
       </
       
       mapper
       
       >
      
      
      
      

       
       
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