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Consider this unique constraint:
ALTER TABLE Posts ADD CONSTRAINT UQ_Posts_Name UNIQUE (Name); Does it automatically create index on Name column?
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When you create a PRIMARY KEY constraint, a unique clustered index on the column or columns is automatically created if a clustered index on the table does not already exist and you do not specify a unique nonclustered index. The primary key column cannot allow NULL values.
Conclusion. Generally there is no functional difference between a unique index and a unique constraint.
A Unique index will be created automatically when you define a PRIMARY KEY or UNIQUE KEY constraints on the specified columns.
To answer to question in bold: Yes, making a field unique does index it like s primary key.
yes it does. See this
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