Difference between SQL Queries

[nikpreek]

Hi All,

I know its very basic question and event I know the answer for this. But I haven't found any proof of this. Is there any difference between thse queries (given below at end of post)? (In terms of performance)

• I'm using SQL 2000 and 2005 both.

• When I check with "Esimated Execution Plan", there is no difference (50% each), but there is very little data in my tables.

• I feel, Query 1 is preferred style of T-SQL developers and Query 2 is preferred Style of PL/SQL developers.

• Query 2 runs much faster is Oracle 9i (I had worked earlier)

Query 1:

Select     Cust.CustomerID, Cust.CustomerCode, Cust.FullCustName, 
    Cycl.CycleID, Cycl.CycleCode,
    Jobs.JobID, Jobs.JobNo, Files.FileID, Files.[FileName], 
    Files.FileSize, Files.Status
From     CustomerCode Cust INNER JOIN Setup Setu ON Cust.CustomerID = Setu.CustomerID 
    INNER JOIN FSECycles Cycl ON Setu.SetupID = Cycl.SetupID
    INNER JOIN FSEJobs Jobs ON Cycl.CycleID = Jobs.CycleID 
    INNER JOIN FSEFiles Files ON Jobs.JobID = Files.JobID
 

Query 2:

Select     Cust.CustomerID, Cust.CustomerCode, Cust.FullCustName, 
    Cycl.CycleID, Cycl.CycleCode,
    Jobs.JobID, Jobs.JobNo, Files.FileID, Files.[FileName], 
    Files.FileSize, Files.Status
From     CustomerCode Cust, Setup Setu, FSECycles Cycl,
    FSEJobs Jobs, FSEFiles Files
Where Cust.CustomerID = Setu.CustomerID 
And Setu.SetupID = Cycl.SetupID
And Cycl.CycleID = Jobs.CycleID
And Jobs.JobID = Files.JobID
 

[debasisdas]

In the first query you are using INNER JOIN syntax explicitely. this is as per ANSI specifications . Performance wise this is faster than the second one.

[nikpreek]

Thanks mate.
Is there any more detailed description available on net?

Thanks in advance.

[debasisdas]

Thanks mate.
Is there any more detailed description available on net?

Yes of course .
But only you need to search for that.