Oracle PL/SQL LONG datatype is a data type in the Oracle database management system used for storing character string data of up to 2 GB in size. It is used to store long character strings that are too large to fit in a VARCHAR2 or CHAR data type. The LONG data type was used in earlier versions of Oracle, but has since been largely replaced by the CLOB (Character Large Object) data type.
The LONG data type is stored in-line in the same table as other data types and is used for storing character strings that do not need to be indexed. Unlike the VARCHAR2 and CHAR data types, the LONG data type does not have a length limitation, but it is limited to a maximum of 2 GB of data.
When using the LONG data type, it is important to keep in mind that it has some limitations. For example, the LONG data type can only be used in the SELECT clause of a query and cannot be used in an INSERT statement or as a column in an indexed view. Additionally, the LONG data type can only be used in a single table and cannot be used in a nested table or an object type.
In general, it is recommended to use the CLOB data type instead of the LONG data type, as it is a more modern and flexible data type. The CLOB data type provides many of the same benefits as the LONG data type, but with the added benefit of being able to be used in a wider range of applications and being more flexible in terms of indexing and other database management tasks.
In conclusion, the Oracle PL/SQL LONG data type is a legacy data type that is still supported for backward compatibility, but it is generally recommended to use the CLOB data type for storing large character strings in Oracle databases.