How to determine the total number of requests that occur during a search using a join of two tables?

The total number of queries when performing a search using a join of two tables depends on the implementation method and the technology used, but in the classic case, an SQL query with JOIN is executed as a single database query.

If we talk about counting internal operations, then:

• When executing a query with JOIN, the database usually performs one query, within which data is combined by keys.
• If the search is implemented at the application level, where a query is first made to the first table, and then a separate query to the second table for each record (for example, the N+1 problem), then the number of queries will be 1 + the number of records from the first table.

To optimize and reduce the number of queries, it is recommended to use a single SQL query with JOIN, for example:

SELECT * FROM table1 t1
JOIN table2 t2 ON t1.id = t2.foreign_id
WHERE t1.some_column = 'value';

Thus, the total number of queries is one, if the query is written correctly and executed on the DBMS side.