MyBatisPlus中的likeLeft和likeRight

素颜马尾好姑娘i 2023-09-25 20:43 4阅读 0赞

**在使用MyBatisPlus来匹配身份证后6位时遇到了likeLeft和likeRight的问题：**

likeLeft时匹配最左边还是匹配最右边？

所以来一个简单的测试（通过打印 “成功/失败” 来判断）

MyBatisPlus代码：

default boolean bindStudent(AppUserBindVO appUserBindVO){
        
            String idLastSix = appUserBindVO.getIdLastSix(); // 获取 appUserBindVO 对象的后六位字符串
            return exists(new LambdaQueryWrapperX<StudentDO>()
                    .eqIfPresent(StudentDO::getStudentNumber,appUserBindVO.getNumber())
                    .eqIfPresent(StudentDO::getName,appUserBindVO.getName())
                    .eqIfPresent(StudentDO::getMobile,appUserBindVO.getMobile())
                    .likeLeft(StudentDO::getIdCard, idLastSix)
            );
        }
        
        
        @Override
        public boolean bindStudent(AppUserBindVO appUserBindVO) {
        
            if (studentMapper.bindStudent(appUserBindVO)){
        
                System.out.println("绑定成功");
            }else System.out.println("绑定失败");
            return studentMapper.bindStudent(appUserBindVO);
        }

MySQL：

![在这里插入图片描述][2032248b6de1452eb4d01db15a73699a.png_pic_center]

用Apifox通过身份证**后6位**请求，**绑定成功**

![在这里插入图片描述][b352370ea9cb4155836717666f79fbe0.png_pic_center]

用Apifox通过身份证**前6位**请求，**绑定失败**

![在这里插入图片描述][27bc6177e0374a849389ff4b046e408a.png_pic_center]

**究其源码：**

public Children like(boolean condition, R column, Object val) {
        
            return this.likeValue(condition, SqlKeyword.LIKE, column, val, SqlLike.DEFAULT);
        }
       public Children likeLeft(boolean condition, R column, Object val) {
        
            return this.likeValue(condition, SqlKeyword.LIKE, column, val, SqlLike.LEFT);
        }
    
        public Children likeRight(boolean condition, R column, Object val) {
        
            return this.likeValue(condition, SqlKeyword.LIKE, column, val, SqlLike.RIGHT);
        }
        
    //===============================================================================
    
    
        protected Children likeValue(boolean condition, SqlKeyword keyword, R column, Object val, SqlLike sqlLike) {
        
            return this.maybeDo(condition, () -> {
        
                this.appendSqlSegments(this.columnToSqlSegment(column), keyword, () -> {
        
                    return this.formatParam((String)null, SqlUtils.concatLike(val, sqlLike));
                });
            });
        }
        
    //==============================================================================
    
    
        public static String concatLike(Object str, SqlLike type) {
        
            switch(type) {
        
            case LEFT:
                return "%" + str;
            case RIGHT:
                return str + "%";
            default:
                return "%" + str + "%";
            }
        }

**最后发现 LEFT 是在左边加 “%” , 所以likeLeft匹配的是右边**

**likeRight则是匹配左边，like则是都可以匹配**

[2032248b6de1452eb4d01db15a73699a.png_pic_center]: https://img-blog.csdnimg.cn/2032248b6de1452eb4d01db15a73699a.png#pic_center
[b352370ea9cb4155836717666f79fbe0.png_pic_center]: https://img-blog.csdnimg.cn/b352370ea9cb4155836717666f79fbe0.png#pic_center
[27bc6177e0374a849389ff4b046e408a.png_pic_center]: https://img-blog.csdnimg.cn/27bc6177e0374a849389ff4b046e408a.png#pic_center