Which of the Following Is a Composite Data Type in PL SQL?
PL/SQL is a powerful procedural language that extends the capabilities of SQL. It provides the ability to define and manipulate complex data structures known as composite data types.
These data types allow you to group related data together, making it easier to organize and work with large amounts of information.
What are Composite Data Types?
Composite data types are user-defined data types that consist of multiple attributes or elements. They are used to represent structured information and can include various scalar and composite elements. PL/SQL supports several composite data types, including:
- Record: A record is a composite data type that allows you to group related fields together. It is similar to a row in a database table and can store multiple values of different data types.
- Table: A table is a collection of records with the same structure. It allows you to store multiple rows of data, each containing the same set of columns.
- Varray: A varray (variable-size array) is an ordered collection of elements with a fixed maximum size.
It allows you to store multiple values of the same data type in a single variable.
- Nested Table: A nested table is similar to a varray but has no fixed size limit. It can dynamically grow or shrink as elements are added or removed.
- Associative Array: An associative array (also known as index-by table or PL/SQL table) is an unordered collection of key-value pairs. It allows you to access elements using arbitrary keys instead of sequential indexes.
Working with Composite Data Types
To work with composite data types in PL/SQL, you need to declare variables or parameters of the appropriate type. You can then manipulate the data using various built-in functions and operators.
For example, to declare a record variable, you can use the following syntax:
DECLARE
person_record employee%ROWTYPE;
BEGIN
— Code goes here
END;
In this example, employee%ROWTYPE is a record type that corresponds to the structure of the employee table in the database. The %ROWTYPE attribute allows you to define a record variable that has the same structure as a table row.
You can then access individual fields of the record using dot notation, like person_record.first_name, person_record.last_name, etc.
Similarly, you can declare variables of other composite data types and perform operations specific to each type. For example, you can add elements to a varray using the .EXTEND() method or iterate over a nested table using a FORALL loop.
In Conclusion
Composite data types in PL/SQL provide a powerful way to organize and manipulate structured information. By grouping related attributes together, you can improve the readability and maintainability of your code.
Whether you are working with records, tables, varrays, nested tables, or associative arrays, understanding how to use these composite data types will greatly enhance your ability to work with complex data structures in PL/SQL.