Uniform SQL Date in Oracle SQL and SQL Server
I am not sure if SQL Server supports ANSI DATE literal, but it is supported in Oracle. The default string literal format is YYYY-MM-DD.
DATE '2015-09-12'
so, if ANSI standard is supported in SQL Server too, then use it. It is simple.
Based on this link, I think you could use the above in both the databases.
WHERE OrderDate='12-09-2015'
Never do that. You are comparing a DATE with a STRING, you might be just lucky to get correct data depending on your locale-specific NLS settings. But, never rely on implicit data type conversion.
Use this for something which works on both:
CAST('2015-09-14' as date)
The cast is executed only once so has no effect on performance.