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Hibernate uses a powerful query language (HQL) that is similar in appearance to SQL. Compared with SQL, however, HQL is fully object-oriented and understands notions like inheritance, polymorphism and association. You can also assign aliases to associated entities or to elements of a collection of values using a join .
I’ve had a lot of feedback on my Oracle Update with Join post. The most common problem people have encountered with this approach is the dreaded “SQL Error: ORA-01779: cannot modify a column which maps to a non key-preserved table”. Tom Kyte has a detailed explanation of this at Ask Tom . However, I thought I would take a moment to address my example scenario.
SQL functions are built into Oracle Database and are available for use in various appropriate SQL statements. Do not confuse SQL functions with user-defined functions written in PL/SQL. If you call a SQL function with an argument of a datatype other than the datatype expected by the SQL function, then Oracle attempts to convert the argument to the expected datatype before performing the SQL function.