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wabs27
Starting Member
4 Posts |
 Posted - 2007-07-19 : 13:17:12
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| Hi,I have a table that contains Customer Information. The Customer table contains a primary key (CustomerID) and then it has a field for CustomerType, and then it has CustomerNumber.CustomerType can be either a person or a company. Based on the value of CustomerType I would either want the CustomerNumber field of the Customer table to be related to the Person table or the Company table since I store different data for each type of data. How can I get around this issue?Thanks |
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tkizer
Almighty SQL Goddess
38200 Posts |
Posted - 2007-07-19 : 13:27:12
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| You won't be able to use a foreign key for this. Perhaps you could enforce referential integrity through a trigger, which is typically the alternative when FKs aren't used.Tara Kizerhttp://weblogs.sqlteam.com/tarad/ |
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Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)
7020 Posts |
Posted - 2007-07-19 : 13:45:59
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| Eliminate the CustomerNumber column, add columns for PersonId and CompanyID, and add FK relationships for those columns. Allow the PersonId and CompanyID columns to be nullable, and add a check constraint to force one or the other to be not null, but not both.CODO ERGO SUM |
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Table Relationships Dependent On Data Value