以下摘自Oracle9i SQL Reference 中[red]The use of LONG values is subject to these restrictions: [/red]■ 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 datatype. 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.■ [red]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.[/red]
