Obsessed with Oracle PL/SQL

A Twitter follower recently asked for more information on user-defined types in the PL/SQL language, and I figured the best way to answer is to offer up this blog post. PL/SQL is a strongly-typed language . Before you can work with a variable or constant, it must be declared with a type (yes, PL/SQL also supports lots of implicit conversions from one type to another, but still, everything must be declared with a type). PL/SQL offers a wide array of pre-defined data types , both in the language natively (such as VARCHAR2, PLS_INTEGER, BOOLEAN, etc.) and in a variety of supplied packages (e.g., the NUMBER_TABLE collection type in the DBMS_SQL package). Data types in PL/SQL can be scalars, such as strings and numbers, or composite (consisting of one or more scalars), such as record types, collection types and object types. You can't really declare your own "user-defined" scalars, though you can define subtypes  from those scalars, which can be very helpful from the p...

I received this question in my In Box last week: In your PL/SQL 101: Working with Collections  article  in Oracle Magazine, the use of "TYPE ... IS ..." is demonstrated.  However I found it's not possible to instantiate an object of the TYPE. It seems that the use of "CREATE TYPE ... AS OBJECT" is required. What are the differences between the 2 ways of creating a user defined data type?  Yes, it can certainly be  confusing when you use the same TYPE statement for arrays and object types, but they cannot all be used in all the same ways in all the same places. So let's go over the differences. PL/SQL Within PL/SQL, you use the TYPE statement to define two different, ahem, types of user-defined types: record and collection. Record A composite datatype consisting of one of more fields. Each field may be of almost any PL/SQL datatype, including another record type or a collection type. You can use the TYPE statement to define a new recor...