The LONG datatype is a very early attempt by Oracle to support very large amounts of data in columns in the database. LONG has been completely superseded by Lobs. The LONG datatype comes with many restrictions, including:
o A table many contain at most one LONG column.
o You cannot create an object type with an attribute of datatype LONG.
o LONG columns cannot be used in WHERE clauses or in integrity constraints.
o You cannot index a LONG column.
o PL/SQL functions that return a LONG value may not be called in SQL.
o PL/SQL functions that have a LONG argument may not be called in SQL
o You cannot reference a LONG column in GROUP BY and ORDER BY clauses.
We hope that you are now convinced: don’t use LONGs in your applications and avoid them whenever possible or try converting it into LOBs or varchar2.