In SQL, it is possible to use the WHERE clause instead of the ON clause to specify join conditions for an inner join.

In SQL, it is possible to use the WHERE clause instead of the ON clause to specify join conditions for an inner join.

• A. No, the ON clause is mandatory for inner joins; WHERE cannot specify join conditions.
• B. Yes, a WHERE clause can be used in place of ON to specify the join condition for inner joins.
• C. Only when joining more than two tables can WHERE substitute for ON.
• D. Using WHERE instead of ON changes the semantics of the join.

Answer: (B)

The idea is that the predicate that defines how two tables should be joined is just a filter on the paired rows. With the explicit INNER JOIN syntax, you usually put that predicate in the ON clause. But if you use the older, comma-style join (listing tables in FROM and then filtering in WHERE), the same join condition can appear in the WHERE clause to achieve the same result for an inner join. For example, joining two tables on a common key can be written either as JOIN ... ON key = key, or as listing the tables and filtering with WHERE key = key. Both approaches keep only the paired rows that satisfy the condition, so they yield the same inner-join result. A helpful caveat: with outer joins, moving the join condition to WHERE can change the outcome (it can turn an outer join into an effective inner join by removing unmatched rows). The key takeaway is that for inner joins, a WHERE clause can specify the join predicate and produce the same result as using ON with explicit join syntax.

The idea is that the predicate that defines how two tables should be joined is just a filter on the paired rows. With the explicit INNER JOIN syntax, you usually put that predicate in the ON clause. But if you use the older, comma-style join (listing tables in FROM and then filtering in WHERE), the same join condition can appear in the WHERE clause to achieve the same result for an inner join. For example, joining two tables on a common key can be written either as JOIN ... ON key = key, or as listing the tables and filtering with WHERE key = key. Both approaches keep only the paired rows that satisfy the condition, so they yield the same inner-join result.

A helpful caveat: with outer joins, moving the join condition to WHERE can change the outcome (it can turn an outer join into an effective inner join by removing unmatched rows). The key takeaway is that for inner joins, a WHERE clause can specify the join predicate and produce the same result as using ON with explicit join syntax.