Definitions for "Unique Key"
Keywords:  row, null, column, suffice, tuple
One or more columns whose values are unique for all rows in a table.
a value that identifies each record (tuple) in a table and distinguishes it from other records. Therefore, one value of a unique key is used only by one record. The simplest type of unique key is a field whose values cannot be repeated, like an employee identity inside a company. Often, one single field doesn't suffice for creating unique values, so a combination of fields must be used. If this still doesn't suffice, then a surrogate key is used. In IB, when you declare an UK, the underlying index is created automatically and it always is in ascending order.
a good candidate for such a field, although the uniqueness of this field is not required
Keywords:  passcode, league, proper, team, ensure
a passcode that will ensure that each team owner in your league is assigned to the proper team