我想让三列在我的数据表中是唯一的
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Column A | Column B | Column C
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Kasun Cham Nimith
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Kasun Cham Rox - This row ok and must be allowed to add.
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Kasun Cham Nimith - but This row must not be allowed to add again,
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如何在 SQL Server 中完成此操作?