How to Create a Conditional WHERE Clause in PostgreSQL

The conditional WHERE clause in PostgreSQL allows for dynamic filtering based on user input parameters, enabling the use of a single static SQL statement to handle various scenarios. To achieve optimal execution plans, one can either build specific queries for each scenario or utilize alternative approaches such as using complex OR conditions or concatenating different queries with UNION ALL. The choice of approach depends on the number of scenarios and the complexity of the query, with UNION ALL offering the best performance when dealing with a limited number of cases. Additionally, PostgreSQL 16 introduces the ability to check generic plans with EXPLAIN, providing more insight into the execution plan's behavior.