SQL Development : Conditional WHERE clauses

If you need to do conditional WHERE clauses, adopt BOOLEAN logic for doing so.
Although CASE statements are more readable, BOOLEAN statements will be evaluated faster.

Further Reading -

• Kevin Attard - Conditional Filtering: Using conditions in T-SQL WHERE clauses 
• Jeff Smith - SQL WHERE clauses: Avoid CASE, use Boolean logic 
• Jeff Smith - Optimizing Conditional WHERE Clauses: Avoiding ORs and CASE Expressions  
• Code Project - Implementing Dynamic WHERE-Clause in Static SQL 
• Split a string to a table using T-SQL