'from_clause' parses the keyword `JOIN` into 'from_alias_clause' in 'from_table_clause' when parsing 'from_join_clause'.
example:
Parse sql SELECT `k1, v1, k2, v2 FROM a JOIN b ON k1 = k2;`.
Now grammar will parse `JOIN` as a `from_alias_clause`, but it should be
a `from_join_clause`;
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