What does the WHERE clause do in an SQL statement?

The WHERE clause in an SQL statement is essential for defining the specific conditions that determine which records will be retrieved from a database. It acts as a filter that narrows down the results based on the criteria set by the user. For example, if you want to select records where a specific column matches a certain value, the WHERE clause specifies that condition, allowing the SQL query to return only the relevant rows that meet the specified criteria. This is crucial for targeting specific data and optimizing the retrieval process, especially in large datasets.

The other options address different SQL functionalities: defining new table structures relates to the creation process of tables, deleting records refers to the removal of entries from a database, and indicating the database to query pertains to which database is being interacted with in the context of a query. Each of these functions serves its purpose within SQL but does not involve the filtering or specification of conditions for data retrieval like the WHERE clause does.