The use of LONG values is subject to these restrictions:
A table can contain only one LONG column.
You cannot create an object type with a LONG attribute.
LONG columns cannot appear in WHERE clauses or in integrity constraints (except that they can appear in NULL and NOT NULL constraints).
LONG columns cannot be indexed.
LONG data cannot be specified in regular expressions.
A stored function cannot return a LONG value.
You can declare a variable or argument of a PL/SQL program unit using the LONG data type. However, you cannot then call the program unit from SQL.
Within a single SQL statement, all LONG columns, updated tables, and locked tables must be located on the same database.
LONG and LONG RAW columns cannot be used in distributed SQL statements and cannot be replicated.
If a table has both LONG and LOB columns, then you cannot bind more than 4000 bytes of data to both the LONG and LOB columns in the same SQL statement. However, you can bind more than 4000 bytes of data to either the LONG or the LOB column.
In addition, LONG columns cannot appear in these parts of SQL statements:
GROUP BY clauses, ORDER BY clauses, or CONNECT BY clauses or with the DISTINCT operator in SELECT statements
The UNIQUE operator of a SELECT statement
The column list of a CREATE CLUSTER statement
The CLUSTER clause of a CREATE MATERIALIZED VIEW statement
SQL built-in functions, expressions, or conditions
SELECT lists of queries containing GROUP BY clauses
SELECT lists of subqueries or queries combined by the UNION, INTERSECT, or MINUS set operators
SELECT lists of CREATE TABLE ... AS SELECT statements
ALTER TABLE ... MOVE statements
SELECT lists in subqueries in INSERT statements
Triggers can use the LONG data type in the following manner:
A SQL statement within a trigger can insert data into a LONG column.
If data from a LONG column can be converted to a constrained data type (such as CHAR and VARCHAR2), then a LONG column can be referenced in a SQL statement within a trigger.
Variables in triggers cannot be declared using the LONG data type.
:NEW and :OLD cannot be used with LONG columns