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Is there a way to loop through a table variable in TSQL without using a cursor?
... depends on the structure and volume of your data.
Note: If you are using SQL Server you would be better served using:
WHILE EXISTS(SELECT * FROM #Temp)
Using COUNT will have to touch every single row in the table, the EXISTS only needs to touch the first one (see Josef's answer below).
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Add unique constraint to combination of two columns
...can often be better to check for this violation first, before just letting SQL Server try to insert the row and returning an exception (exceptions are expensive).
http://www.sqlperformance.com/2012/08/t-sql-queries/error-handling
http://www.mssqltips.com/sqlservertip/2632/checking-for-potential-co...
App Inventor 2 UDP网络通信教程 - 发送和接收UDP数据包 · App Inventor 2 中文网
...能用吗？
Q：如何实现 UDP 和 TCP 混合使用？
性能优化建议
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概述
UDP（User Datagram Protocol，用户数据报协议）是一种无连接的传输层协议，常用于局域网设备发...
Subqueries vs joins
...dependent of the containing query) will execute once at the beginning. The SQL engine makes this distinction automatically.
But, yeah, explain-plan will give you the dirty details.
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How to generate a range of numbers between two numbers?
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There's a maximum maxrecursion set to 32767 (in SQL Server 2012).
– BProv
Dec 2 '16 at 16:25
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Proper Linq where clauses
...ually makes depends on the implementation of Where being called. If it's a SQL-based provider, I'd expect the two to end up creating the same SQL. If it's in LINQ to Objects, the second will have fewer levels of indirection (there'll be just two iterators involved instead of four). Whether those lev...
Declaring a default constraint when creating a table
I am creating a new table in Microsoft SQL server 2000 by writing the code instead of using the GUI, I am trying to learn how to do it "the manual way".
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Why is iterating through a large Django QuerySet consuming massive amounts of memory?
...hanks for the great answer, @eternicode. In the end we dropped down to raw SQL for the desired database-level iteration.
– davidchambers
Aug 13 '11 at 21:15
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MySQL order by before group by
... table, on both values you will return the full details of that post.
See SQL Fiddle with Demo.
To expand on my comments about using a subquery to accurate return this data.
MySQL does not force you to GROUP BY every column that you include in the SELECT list. As a result, if you only GROUP BY ...
Condition within JOIN or WHERE
...eports joining 5-6 tables on few millions records. Perf improves by 30% - sql server 2012
– Shahdat
Oct 6 '16 at 16:33
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