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Do You Doubt Design Bd In Sqlyog?

forums › forums › SQLyog › Query Builder and Schema Designer › Do You Doubt Design Bd In Sqlyog?

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    • December 31, 2010 at 4:27 pm #12217
      Saulo Daniel Villamizar P
      Member

      Hello Happy New Year…

      My doubt is the following one I have two tables with a relation one to many, but the table father has a primary key composed by several fields. Since one relates both tables? The reason is that the relation does not appear as one to many but many to many.

    • December 31, 2010 at 7:12 pm #31780
      peterlaursen
      Participant

      IF you have a multicolumn PK each column may have duplicated values – for instance the two columns may have vaules (a,:cool: and (x.y) combined like this.

      Code:
      a x

      b y

      a y

      b x

      Neither column can be guaranteed to be unique with such Primary key and that is why a Foreign Key from a 'child' table referencing either of the two columns defines a many-many relationship. That is why it is correct what the Schema Designer does here!

      If you want to define a many-one relationship without changing the Primary Key you can add a Unique Key on the 'parent' column alone.

    • December 31, 2010 at 7:48 pm #31781
      peterlaursen
      Participant

      the smiley should have been a 'b'!

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