weixin_44084713的博客

SELECT SENSORDATE FROM "Z_SENSOR" GROUP BY SENSORDATE HAVING COUNT(*)>1

1.减函数DATE_SUB--date_subselectDATE_SUB('2021-12-17',INTERVAL 1 DAY) as dayTime,--昨天DATE_SUB('2021-12-17',INTERVAL 1 MONTH) as monthTime,--上个月DATE_SUB('2021-12-17',INTERVAL 1 YEAR) as yearTime;--去年![在这里插入图片描述](https://img-blog.csdnimg.cn/6e0eec0dfa1a4a

今天出现一个奇怪的现象，一个表中只有8条数据，在Navicat中执行SQL语句，十几秒都没有结果数据库的其他表均能正常显示。网上调查得知可能是表出现死锁情况解决方案如下：1.查看被锁表：select request_session_id spid,OBJECT_NAME(resource_associated_entity_id) tableName from sys.dm_tran_locks where resource_type='OBJECT'spid 代表锁表进程

substring_indexCASE B.DataType in (‘A’,‘B’,‘C’)WHENB.ShowValue =‘5’THENsubstring_index(B.Unit,’/’,-1)whenB.ShowValue =‘6’THENsubstring_index(B.Unit,’/’,1)ELSE B.UnitEND Unit注意：：1代表"/“左边的字符...