SQL Server将多个查询作为一个查询运行

Question

I've got two different SQL queries that I need to run at once. But since I am using inner joins in both of them, I can't just join them. Is there a way to do this? Also, do you think that much normalization could cause problems?

SELECT S.SchoolName,Sd.DepartmentName,E.GraduationDate 
FROM   Education E 
           INNER JOIN SchoolDepartment Sd ON Sd.DepartmentID = E.DepartmentID 
           JOIN School S ON S.SchoolID = Sd.SchoolID

SELECT c.CompanyName,dt.DepartmentName, pl.PositionLevelName 
FROM   Employee Ee 
           INNER JOIN Position P ON Ee.PositionID = P.PositionID  
           JOIN Company c ON c.CompanyID = P.CompanyID 
           JOIN Department De ON De.DepartmentID=P.DepartmentID 
           JOIN DepartmentType dt ON dt.DepartmentName = De.DepartmentTypeID  
           JOIN PositionLevel pl ON pl.PositionLevelID=P.PositionLevelID    

Answer 1

It seems like you're attempting to get two distinct sets of data, so it's not the worst thing in the world to run two queries.

Per your comment: I'm sure Facebook queries several stores when they load your profile page, but they're making heavy use of data caching, so they may cache your profile object(s) to reduce database hits.

Answer 2

You haven't indicated how they both are connected to a profile and whether each set is going to have many rows which are unrelated to each other. If each just returns a single row and both are related to the profile (related in the sense of relational database - attributes "related" to a key - perhaps your profile), there there probably is a realistic way to combine them into a single result set (ie a relation, or table).

There are a few strategies you can use if the sets on not really related in that sense.

1. Make a single stored procedure or batch both in the same command which returns both result sets in sequence and use ADO.NET's feature to get the next result set on your reader.

2. Make two sequential calls to the database.

3. Use ASP and ADO's asynchronous features to make two simultaneous calls to the database and handle the completions - this can be useful for high-volume sites, since control is returned to the page once they are completed, freeing up threads.

Answer 3

I am trying to do something similar. I am actually trying to group lines by multiple criteria that are different into one data set. What I am doing is querying all of the data into a temp table then querytin that temp table into the different views then unioning it back. This way it shows the different views. For example. Line 1 includes cat1 cat2 and cat3. Line 2 is just cat 2 and cat 3. And line 3 is Cat1 - cat8. The data is all the same just different slices of it. So multiple trips to the database to query it isn't worth the overhead. I can query the temp multiple times to get my slices then union them together into one view. Alternatively if you need these views and they change you can create a table with the groupings you want in a one to many. With that three tiered approach you can join and get the sums in one step.

Answer 4

如果字段具有相同的数据类型（查询1中的列与查询2的相同数据类型匹配），则可以使用UNION组合两个查询，否则如果无法加入它们则不可能。

Answer 5

No, it is not possible on one connection. You need to open two connections and have a server powerfull enough to handle that (which means more than one core, which you mostl likely have).

Note that I answer your question - most others dont seem to.

I've got two different SQL queries that I need to run at once

That is not how it works in SQ LServer. If you writee thm into one batch, they still execute one after the other, not at the same time. Not sure it makes sense for them to run at the same time, but that is what you ask for.

But I have software doing hundreds of SQL at the same time given a powerfull enough applkication server (24 cores), a powerfull enough Oracle RAC (48 cores on 2 machines with hyperthreading = 96 parallel threads).