Sql server doesn't like the aggregate function in the set command. It does work as a SELECT and I can get the data I'm looking for so should I use that answer and try and use it as a subquery or cursor and then run the update into Customers?

2015年7月9日 · Improperly configured SQL Servers will do poorly at this type of query. Transaction logs which are too small and/or share the same disks as the data files will often incur severe performance penalties when working with large rows.

2013年2月8日 · Something like this should work using a subquery to get your MAX UnitPrice associated with each CategoryId. SELECT DISTINCT IP.* FROM InventoryPart IP JOIN CustOrderLine COL ON IP.PartNumber = COL.PartNumber JOIN ( SELECT IP.CategoryID, MAX(COL.UnitPrice) MaxPrice FROM InventoryPart IP INNER JOIN CustOrderLine COL ON …

2012年5月30日 · You don't need the correlated subquery. You seem to have a relatively simple join, albeit on several fields at the same time. The following FROM clause extracts the conditions from inside the subquery that refer to both tables and move them outside into the JOIN clause.

2013年6月27日 · A Correlated subquery is a subquery that is evaluated once for each row processed by the outer query or main query. Execute the Inner query based on the value fetched by the Outer query all the values returned by the main query are matched.

2013年8月10日 · In most cases I prefer to use APPLY operator instead of correlated subquery. In your case I would suggest the next solution: SELECT a.assetnum as Asset, a.assettag as Asset_Tag, a.manufacturer as Manufacturer, a.serialnum as Serial, a.description as Description, CASE a.isrunning WHEN 1 THEN 'Operational' WHEN 0 THEN 'Down' END AS Condition, …

2012年7月21日 · The efficiency gain that CAN result from using EXISTS in a correlated subquery comes from the fact that as soon as EXISTS returns TRUE, the subquery stops scanning records and returns a result. Similarly, a subquery which employs NOT EXISTS will return as soon as ANY record matches the criteria in the WHERE statement of the subquery.

2012年2月6日 · You are expecting the UPDATE to be executed with one evaluation of the subquery per row. But it is one statement that is first evaluated - for all affected rows - and then the rows are changed (updated).

2017年1月24日 · Subqueries are not inherently good or bad (one could argue rather that SQL optimizers are bad, rather than subqueries). Your example is not correlated at all. The question of whether a particular query is efficient or not requires analyzing the execution plan.

A correlated subquery means it can be re-written as a JOIN - the correlation is the JOIN criteria. You can define multiple views in Subquery Factoring - if you provided more detail I could tailor the answer better.