Detrimental effects of predicates on estimation of cardinality with the query processor.

• Queries with predicates that use comparison operators between different columns of the same table.

• Queries with predicates that use operators, and any one of the following are true:
   o There are no statistics on the columns involved on either side of the operators.
   o The distribution of values in the statistics is not uniform, but the query seeks a highly selective value set. This situation can be especially true if the operator is anything other than the equality (=) operator.
   o The predicate uses the not equal to (!=) comparison operator or the NOT logical operator.

• Queries that use any of the SQL Server built-in functions or a scalar-valued, user-defined function whose argument is not a constant value.

• Queries that involve joining columns through arithmetic or string concatenation operators.

• Queries that compare variables whose values are not known when the query is compiled and optimized.