把以下代码转为lambdaquerywapper:SELECT knowledge_type, knowledge_desc,ana FROM xy_custom_knowledge B LEFT JOIN (SELECT attachment_name ana,head_id FROM xy_custom_knowledge_file a ) C on C.head_id = B.id
时间: 2024-03-06 19:49:52 浏览: 21
把以上 SQL 语句转换为 LambdaQueryWrapper,可以如下实现:
```
LambdaQueryWrapper<XyCustomKnowledge> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.select(XyCustomKnowledge::getKnowledgeType, XyCustomKnowledge::getKnowledgeDesc,
Sqls.custom("C.attachment_name as ana"));
lambdaQueryWrapper.leftJoin(XyCustomKnowledgeFile.class,
XyCustomKnowledge::getId, XyCustomKnowledgeFile::getHeadId);
```
其中,LambdaQueryWrapper 的 select 方法用于指定查询的字段,这里使用了方法引用的方式指定了 XyCustomKnowledge 实体中的三个字段。Sqls.custom 方法用于指定一个 SQL 片段,这里用于将查询结果中的字段名自定义为 ana。LambdaQueryWrapper 的 leftJoin 方法用于设置左连接,第一个参数为关联的表的实体类,第二个参数为当前表的主键字段,第三个参数为关联表的外键字段。
相关问题
将以下代码转换为@select注解:SELECT knowledge_type, knowledge_desc,ana FROM xy_custom_knowledge B LEFT JOIN (SELECT attachment_name ana,head_id FROM xy_custom_knowledge_file a ) C on C.head_id = B.id WHERE ana LIKE "%ruoyi%" OR knowledge_desc LIKE "%ruoyi%" OR knowledge_desc LIKE "%ruoyi%"
这个问题和你上一次提出的问题是相同的。已经为您转换成@select注解的代码如下:
```java
@select("knowledge_type, knowledge_desc, ana")
FROM("xy_custom_knowledge B")
LEFT_JOIN("(SELECT attachment_name ana,head_id FROM xy_custom_knowledge_file a ) C on C.head_id = B.id")
WHERE("ana LIKE '%ruoyi%' OR knowledge_desc LIKE '%ruoyi%' OR knowledge_desc LIKE '%ruoyi%'")
```
ImportError: cannot import name 'Callable' from 'collections' (D:\ana\1\lib\collections\__init__.py)
根据引用\[1\]中的内容,这个错误是由于在导入collections模块时,无法找到名为'Callable'的引用。根据引用\[2\]中的内容,可以尝试通过更改文件来解决这个问题。打开报错路径中的文件,在出错的代码行之前,将导入语句修改为以下形式:
```python
try:
from collections.abc import Callable
except ImportError:
from collections import Callable
```
这样可以先尝试从collections.abc模块中导入'Callable',如果导入失败则再从collections模块中导入。这样应该可以解决ImportError的问题。
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