Check Constraints

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Check Constraints

testaj27

SSC Journeyman

Points: 81
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May 31, 2010 at 8:17 am

#387047

Hello. I am a student and am trying to complete a homework assignment but can't figure it out. I am supposed to add a check constraint to one of my database tables that requires the Password field to be at least 8 characters. I have tried everything that was taught to me and can not come up with the solution. Can someone please point me in the right direction?

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Ninja's_RGR'us SSC Guru Points: 294069 More actions · Answer 1

what have you tried and what is wrong with that you've tried?

Lowell SSC Guru Points: 323504 More actions · Answer 2

there are two functions you can use to check the length of a string :

LEN(SomeField)

--or

DATALENGTH(SomeField)

both return integer values. I believe that your check constraint would have to use either of those functions to accomplish your assignment.

Lowell

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Bajrang SSCrazy Points: 2074 More actions · Answer 3

Use Len(Ltrim(Rtrim(Column_Name))) in your Check Constraint

-RP

Oleg Netchaev SSCertifiable Points: 5276 More actions · Answer 4

Rups (6/2/2010)
Use Len(Ltrim(Rtrim(Column_Name))) in your Check Constraint

This is a good solution, but rtrim is not needed. Len function ignores the trailing (but not leading) spaces. In other words len('hello ') is equal to 5, and therefore

len(ltrim(Column_name)) > 8

should do the the trick as well. For this solution, Len is also safer than datalength for 2 reasons:

If the passwords are implemented as nvarchar then datalength returns twice the number as len

Datalength does not ingore trailing spaces.

Oleg