I have a situation where a number of foreign keys are referencing a column in Table "A". I would like to change the length of the column in table "A". What is the best way to accomplish this in SQL Server 2008 R2? I am really hoping I don't have to drop all 30 foreign key constraints and re-create them again...

  • Why do you need ilastic field lengths? There's a max length anyway allowed for a field. At the point of designing, would have set to max...
    – bonCodigo
    Commented Dec 28, 2012 at 19:59
  • bonCodigo -- hindsight is 20/20... But this is a situation I am facing now.
    – Denis
    Commented Dec 28, 2012 at 20:01
  • and (b) primary key fields can't be varchar(max)
    – Denis
    Commented Dec 28, 2012 at 20:01
  • There you go the answer ;) Summarize my comments.
    – bonCodigo
    Commented Dec 28, 2012 at 20:08
  • @bonCodigo - See varchar(max) everywhere? for some reasons why that is not a good idea. Commented Dec 30, 2012 at 17:43

2 Answers 2

  1. Script out Drop and Create All 30 JF.
  2. Drop all 30 KF
  3. Alter Columns
  4. Create all 30 KF
  • can't I disable all the foreign keys somehow?
    – Denis
    Commented Dec 28, 2012 at 20:04
  • there is no disable option in MSSQL
    – Hiten004
    Commented Dec 28, 2012 at 20:07
  • ugh... was hoping I didn't have to do it... I have to teach my users to abbreviate :-)
    – Denis
    Commented Dec 28, 2012 at 20:23
  • There is a way you can disable foreign keys on tables: ALTER TABLE TableName NOCHECK CONSTRAINT ALL. This however won't help when altering primary key/unique constraint columns, but it's useful information.
    – user2235
    Commented Jan 3, 2013 at 2:25
  • @fortheworld - tried that. That only disable the constraints for operations like INSERT/UPDATE/DELETE. Doesn't disable the constraints when you are changing field lengths.
    – Denis
    Commented Jan 7, 2013 at 15:03

You can change column length in TableA via GUI (Management Studio), and all the foreign keys will be changed automatically.

  • Good for small things that aren't critical but I just had this delete one of my main tables and not restore it when it timed out creating foreign keys through the diagram editor.
    – DShook
    Commented Jun 4, 2014 at 20:38

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