How can PHP developers ensure that keys are properly specified and connected in SQL join statements to avoid errors?

To ensure that keys are properly specified and connected in SQL join statements to avoid errors, PHP developers should carefully review the column names in the tables being joined and make sure they are correctly referenced in the join condition. It is important to use table aliases to avoid ambiguity and to specify the keys explicitly in the ON clause of the join statement.

$query = "SELECT * 
          FROM table1 
          INNER JOIN table2 ON table1.id = table2.table1_id";