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When is ordering not optional in index creation?
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[QUOTE="cronxeh, post: 6063861, member: 9787"] If you have data in your table (relations) that has duplicate entries and you try to create a unique index using that key, you should not be able to. For example you can have people with same names, dates of birth, address, department id, title, etc. Example where it will fail: [URL]https://stackoverflow.com/questions/33361281/how-to-create-unique-index-for-existing-table-in-mysql-which-contains-records[/URL] You should choose something unique like SSN# or EmployeeID for unique index creation, i.e likely to be a unique table: EmployeeID FirstName LastName Title Department Salary vs unlikely to be unique: FirstName Gender Department [/QUOTE]
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When is ordering not optional in index creation?
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