## CASTing

 Author Message Carlo Romagnano SSCrazy Eights Group: General Forum Members Points: 9352 Visits: 3441 Comments posted to this topic are about the item CASTing John Mitchell-245523 SSC Guru Group: General Forum Members Points: 54590 Visits: 16980 Sorry, I don't understand. What CAST to nvarchar(800)? Is there a typo in the question?John Jerry Hung SSCertifiable Group: General Forum Members Points: 5374 Visits: 1208 me a little bit confused too, what's the difference between this Question, and the one 2 days ago?TODAYCASTingSecond question of day: what is the len of @c?declare @c varchar(800)set @c = N'hello' + replicate('-',800)print len(@c)print @c Sorry - you were wrongCorrect answer: 800Explanation: The CAST to nvarchar(800) has a maximum 4000 character len. The CAST then to varchar(800) fits in that space, so the len is 8002 days agoCASTingFirst question of day: what is the len of @c?declare @c varchar(8000)set @c = N'hello' + replicate('-',8000)print len(@c)print @cYou got it right!Correct answer: 4000Explanation: The CAST to NVARCHAR(4000) means that the maximum len is 4000, then the cast to varchar(8000) allows more characters, but the string is already truncated. SQLServerNewbieMCITP: Database Administrator SQL Server 2005 steveb. SSCoach Group: General Forum Members Points: 17234 Visits: 7195 The one two days ago was casting to a length greater than the nvarchar data type max of 4000, so the length was truncated to 4000. The one today was casting to a length less than 4000 so it stayed the same. Jerry Hung SSCertifiable Group: General Forum Members Points: 5374 Visits: 1208 Does that mean this 2 lines below, converts @c to nvarchar(8000)?meaning ANY casting to nvarchar always give it maximum length of 8000?declare @c varchar(800)set @c = N'hello' I think I got lost by reading this sentence ... maybe I shouldn't read it anymoreThe CAST to nvarchar(800) has a maximum 4000 character len. SQLServerNewbieMCITP: Database Administrator SQL Server 2005 steveb. SSCoach Group: General Forum Members Points: 17234 Visits: 7195 nvarchar has a max length of 4000 not 8000the 'N' in this statment converts it;`set @c = N'hello'` TheRedneckDBA SSCertifiable Group: General Forum Members Points: 5920 Visits: 2621 Good question of the day...I totally fell for it! The Redneck DBA John Mitchell-245523 SSC Guru Group: General Forum Members Points: 54590 Visits: 16980 Yeah, so did I. I see what happened now.John Biggles-581128 SSC Veteran Group: General Forum Members Points: 259 Visits: 208 Great question.Didn't fall into the trap, but only because I remembered the question 2 days ago and thought there must be something else going on.Its got me thinking a lot more about types and implicit conversions. Thanks Christian Buettner-167247 SSCertifiable Group: General Forum Members Points: 6763 Visits: 3889 I think these two QODs really show how evil implicit type conversions are.Id rather spend this one second on explicit type conversion than on reviewing such code for possible data loss caused by implicit conversion. I had to look at this QOD for at least 5 seconds before I made my choice. Sum this up for all your code and then tell me: wouldn't it be great if the compiler told you when you had missed a type conversion?Sure, you have a test team, but why not catch an error in the first place?Isn't a database a realm where datatypes should be handled in the most strict way?Just some thoughts in the late evening :-) Best Regards,Chris Büttner