In a Transact-SQL book (Ramalho Series) it is said:
Implicitly converts one expression from data types to another. CAST is a synonym for CONVERT.
What do you mean by CAST is synonymous with CONVERT? What is the usage orientation of one and the other? Is there a performance implication between the two?
CONVERT is a specific function of SQL Server and CAST is default ANSI .
There is a conversion table that can be used to decide whether or not to use some conversion function for each case:
Followingtheinformationinthetable,ifitisnecessarytoconvertfromvarchartodatewecandoimplicitly:
DECLARE@dataDATE='2017-06-21';Ortoconvertadatetimetotimestampyoumustdoitexplicitly:
DECLARE@dataDATETIME=getdate();DECLARE@horaTIMESTAMP=CAST(@dataASTIMESTAMP);Asforperformance,thereisnorule.Foreachtypethereisaminimumvariationbetweenthetwouses.
References:
CAST and CONVERT (Transact-SQL)