Unique Constraint on a SUBSTRING?

• Ariadne

  SSCrazy

  Points: 2044

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  October 20, 2003 at 12:36 pm

  #83336

  Anyone have any idea how to put a constraint on a table that requires a UNIQUE First Char in the column AND that it only has to be UNIQUE if another column is equal to 1?

  Well, that doesn't say it quite right. How about the following Data Set:

  Row1, Col1: Jane Smith

  Row1, Col2: 1

  Row2, Col1: Harry Belafonte

  Row2, Col2: 1

  Row3, Col1: Jesse Goodberry

  Row3, Col2: 2

  I don't want another 'J' or 'H' Name in the Column if the Col2 = 1

  I don't want another 'J' Name in the Column if the Col2 = 2,

  But Since I don't have an 'H' Name where Col2 = 2, then it would be okay until I did have one.

  That make sense?

  Phew...

• Jonathan

  SSC-Insane

  Points: 20427

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  October 20, 2003 at 2:30 pm

  #478866

  If you're using SQL Server 2000, you could use a UDF in a check constraint. Otherwise you could use a trigger.

  --Jonathan

  
  
  --Jonathan