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What Is The Difference Between Key And Duplicate Key? |
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Answer» Whenever a field is a key field we cannot have duplicate values in that field. Key is USED to identify the field as the search criterion that uniquely IDENTIFIES each ROW. Duplicate values are allowed, for example in composite keys like if we have 4 fields at LEAST one field should be unique ex: in job table emplid, emplrcd, effdt and effseq Whenever a field is a key field we cannot have duplicate values in that field. Key is used to identify the field as the search criterion that uniquely identifies each row. Duplicate values are allowed, for example in composite keys like if we have 4 fields at least one field should be unique ex: in job table emplid, emplrcd, effdt and effseq |
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