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Preventing Duplicate Values During Data Insertion
Problem Statement:
Within a table named "Delegates," which contains unique member information as well as range fields "FromYr" and "ToYr," data insertion using user inputs risks the duplication of members for the same year.
Solution:
To address this issue and ensure data integrity, we can leverage the MERGE statement. The MERGE statement allows us to perform a conditional insertion, updating the record only if it does not already exist within the table.
Implementation:
<code class="sql">MERGE INTO Delegates D USING (values(@MemNo, @FromYr,@ToYr)) X ([MemNo],[FromYr],[ToYr]) ON (insert unique key join) WHEN NOT MATCHED BY TARGET THEN INSERT ([MemNo],[FromYr],[ToYr])) VALUES (X.[MemNo],X.[FromYr],X.[ToYr]);</code>
Explanation:
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