I have 2 tables, eg. EarningDescriptions and EmployeeDetails with 1 column in each to simplify the question. EarningsLineNo in EarningsDescriptions and EmployeeCode in EmployeeDetails.
i created another table that references 2 columns in that table to the 2 columns in the other 2 tables as such :
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Create table Earnings
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(
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EarningLineNo int references EarningDescriptions(EarningLineNo) not null,
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EmployeeCode nvarchar(50) references EmployeeDetails(EmployeeCode) not null,
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EarningAmount decimal not null,
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Primary key (EarningLineNo, EmployeeCode)
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)
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I used a composite key because the EarningLineNo and EmployeeCode in the new table will be used over and over again. but the same combination wld not be for instance. 1-1. 2-3 etc
I would like to knw what the referencing to the other columns is actually for and if its necessary or not ?
Is it for saving purposes or maybe making sure information is similar in the columns in both tables....
