select 'selectdatabase_id, db_name(database_id) dbname, database_transaction_begin_time, database_transaction_state, database_transaction_log_record_count, database_transaction_log_bytes_used, database_transaction_begin_lsn, stran.session_idfromsys.dm_tran_database_transactions ...
<foreach collection="versionQueryParam.bizIdList" separator="," index="index" open="(" close=")" item="item"> #{item} </foreach> </if> group by biz_id) b on concat(a.biz_id,a.gmt_create) = concat(b.biz_id,b.gmt_create) </select> </mapper> 1. 2. 3. 4. 5. 6. 7....
How to select top 1 from union? how to select top 1 record per group How to Send a Message from Stored Procedure to the application How to Send PDF file as an attachment with sp_send_dbmail? How to send SQL select output to a txt/csv file How to set a variable in an if exists...
To see which indexes the query optimizer uses for a specific query, in SQL Server Management Studio, on the Query menu, select Include Actual Execution Plan.Don't always equate index usage with good performance, and good performance with efficient index use. If using an index always help...
2 我用sql实现过的复杂逻辑有TAD计算、内积运算、同环比、cube表设计、循环、递归（hive不支持）等等，...
each database.IF( OBJECT_id (N'tempdb..#dm_db_log_space_usage')isnotnull)BEGINDROPTABLE#dm_db_log_space_usageENDSELECT*INTO#dm_db_log_space_usageFROMsys.dm_db_log_space_usagewhere1=0DECLARElog_spaceCURSORFORSELECTNAMEFROMsys.databasesOPENlog_spaceFETCHNEXT...
SELECTt1.*FROMdevice_recordt1INNERJOIN(SELECTdevice_id,app_version,MAX(create_time)ASmax_dateFROM...
SELECT SUM(UnitPrice*OrderQty*(1.00-UnitPriceDiscount)) AS Revenue, OrderDate, ProductID, COUNT_BIG(*) AS COUNT FROM Sales.SalesOrderDetail AS od, Sales.SalesOrderHeader AS o WHERE od.SalesOrderID = o.SalesOrderID GROUP BY OrderDate, ProductID; ...
正在处理SELECT查询的记录,同时正在把结果发送给客户端。 Sorting for group 正在为GROUP BY做排序。 Sorting for order 正在为ORDER BY做排序。 Opening tables 这个过程应该会很快,除非受到其他因素的干扰。例如,在执ALTER TABLE或LOCK TABLE语句行完以前,数据表无法被其他线程打开。正尝试打开一个表。
GROUP BY HAVING SELECT DISTINCT UNION ORDER BY 关于SQL 语句的执行顺序,有三个值得我们注意的地方: 1.FROM 才是 SQL 语句执行的第一步,并非 SELECT 。数据库在执行 SQL 语句的第一步是将数据从硬盘加载到数据缓冲区中,以便对这些数据进行操作。