# General SELECT Statement Considerations

- Before composing an SQL statement, you should have in front of you the ERD of the tables involved in that SQL. You should make sure you fully understand the relationships between the tables.
- As you may know, an SQL may return a single record or a set of records as its result set. When a set is to be returned, it is managed by a cursor that loops through that set and issues a separate database call for each record in the set.
- Therefore, when you design your SQL, think carefully if the task can be easily achieved in a single SQL or rather that the nature of task is such that a row-by-row processing would make more sense. Examples for the latter could be a list processing or simply because the calculation per row is too complicated to be handled by the database.

Parent topic: Composing a SELECT Statement