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Collections Oracle Database PL/SQL 10g Programming

Collections Oracle Database PL/SQL 10g Programming. Chapter 6. Collections. Collection Types VARRAY Collections Nested Table Collections Associative Array Collections Collection API. Collections Collection Types: Definition. Collections are lists. Collections are ordered or unordered.

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Collections Oracle Database PL/SQL 10g Programming

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  1. CollectionsOracle Database PL/SQL 10g Programming Chapter 6

  2. Collections • Collection Types • VARRAY Collections • Nested Table Collections • Associative Array Collections • Collection API Oracle Database PL/SQL 10g Programming (Chapter 6)

  3. CollectionsCollection Types: Definition • Collections are lists. • Collections are ordered or unordered. • Ordered lists are indexed by numbers. • Unordered lists are indexed by unique strings. • Collection elements can be: • Scalar variables • Compound variables Oracle Database PL/SQL 10g Programming (Chapter 6)

  4. CollectionsCollection Types: VARRAY • VARRAY collections are densely populated structures, indexed by sequential numbers. • VARRAY collections have an initial maximum size. • VARRAY collections can be used as column data types. Oracle Database PL/SQL 10g Programming (Chapter 6)

  5. CollectionsCollection Types: Nested Table • Nested tables are densely populated structures, indexed by sequential numbers. • Nested tables are have no maximum size. • Nested tables can be used as column data types. Oracle Database PL/SQL 10g Programming (Chapter 6)

  6. CollectionsCollection Types: Associative Arrays • Associative arrays are sparsely populated structures, indexed by unique numbers or strings. • Associative arrays have no maximum size. • Associative arrays cannot be used as column data types. Oracle Database PL/SQL 10g Programming (Chapter 6)

  7. CollectionsCollection Types: Multiset Operators • MULTISET EXCEPT This operator removes one set from another, like the SQL MINUS operator. • MULTISET INTERSECT This operator takes two sets and merges them into a new set that contains one copy of elements found in both original sets, like the SQL INTERSECT operator. • MULTISET UNION This operator takes two sets and merges them into a new set without eliminating duplicate values, like the UNION ALL operator. • SET This operator removes duplicates from a set and acts like the DISTINCT operator in a SQL statement. Oracle Database PL/SQL 10g Programming (Chapter 6)

  8. CollectionsVARRAY Collection Types: Rules • VARRAY data types can be defined: • As PL/SQL user-defined types. • As SQL collection data types of scalar variables. • As SQL collection data types of compound, object type, variables. • VARRAY data types require explicit construction. • VARRAY data types allocate space at construction or by calling the Oracle Collection API EXTEND methods to allocate space for an element or set of elements. Oracle Database PL/SQL 10g Programming (Chapter 6)

  9. CollectionsVARRAY Collection Types: SQL Declaration -- Declare VARRAY SQL data type. CREATE [OR REPLACE]TYPEnumber_list AS VARRAY(3) OF NUMBER; Oracle Database PL/SQL 10g Programming (Chapter 6)

  10. CollectionsVARRAY Collection Types: PL/SQL Declaration DECLARE -- Declare VARRAY PL/SQL data type. TYPEnumber_listIS VARRAY(3) OF NUMBER; -- Create a list without any allocated space. empty_scalar_list NUMBER_LIST := NUMBER_LIST(); -- Create a list of NULL values with two allocated space. null_scalar_list NUMBER_LIST := NUMBER_LIST(NULL,NULL); -- Create a list of values with three allocated space. value_scalar_list NUMBER_LIST := NUMBER_LIST(1,2,3); BEGIN … next_slide … END; / Oracle Database PL/SQL 10g Programming (Chapter 6)

  11. CollectionsVARRAY Collection Types: PL/SQL Assignment DECLARE … prior_slide … BEGIN empty_scalar_list.EXTEND; empty_scalar_list(1) := 1829; END; / Oracle Database PL/SQL 10g Programming (Chapter 6)

  12. CollectionsNested Table Collection Types: Rules • Nested table data types can be defined: • As PL/SQL user-defined types. • As SQL collection data types of scalar variables. • As SQL collection data types of compound, object type, variables. • Nested table data types require explicit construction. • Nested table data types allocate space at construction or by calling the Oracle Collection API EXTEND methods to allocate space for an element or set of elements. Oracle Database PL/SQL 10g Programming (Chapter 6)

  13. CollectionsNested Table Collection Types: SQL Declaration -- Declare VARRAY SQL data type. CREATE [OR REPLACE]TYPEnumber_list AS TABLE OF NUMBER; Oracle Database PL/SQL 10g Programming (Chapter 6)

  14. CollectionsNested Table Collection Types: PL/SQL Declaration DECLARE -- Declare VARRAY PL/SQL data type. TYPEnumber_listIS TABLE OF NUMBER; -- Create a list without any allocated space. empty_scalar_list NUMBER_LIST := NUMBER_LIST(); -- Create a list of NULL values with two allocated space. null_scalar_list NUMBER_LIST := NUMBER_LIST(NULL,NULL); -- Create a list of values with three allocated space. value_scalar_list NUMBER_LIST := NUMBER_LIST(1,2,3); BEGIN … next_slide … END; / Oracle Database PL/SQL 10g Programming (Chapter 6)

  15. CollectionsAssociative Array Collection Types: Rules • Associative Array data types can be defined as PL/SQL user-defined types. • Associative Array data types cannot be defined as SQL collection data types. • Associative Array data types do not require explicit construction. • Associative Array data types require element by element assignment, or bulk assignments. • Associative Array data types do not require explicit space allocation. • Associative Array data types can use the Oracle Collection API. Oracle Database PL/SQL 10g Programming (Chapter 6)

  16. CollectionsNested Table Collection Types: PL/SQL Usage DECLARE -- Declare VARRAY PL/SQL data type. TYPEnumber_listIS TABLE OF NUMBER INDEX BY BINARY_INTEGER; -- Declare a variable. empty_scalar_list NUMBER_LIST; BEGIN empty_scalar_list(1) := 1829; END; / Oracle Database PL/SQL 10g Programming (Chapter 6)

  17. CollectionsCOLLECTION API: Methods • COUNT a method that returns the number of elements in a collection. • DELETE(n) a method that takes a single formal parameter that is an index value, and it removes the element pointed to by the equivalent index value. • DELETE(n,m) a method that takes two formal parameter index values, and it removes a range of elements pointed to by the equivalent index value. • EXISTS(n) a method that takes one formal parameter index value, and returns TRUE if found in the collection and FALSE if not. If the collection is a null element structure, the method also returns FALSE. Oracle Database PL/SQL 10g Programming (Chapter 6)

  18. CollectionsCOLLECTION API: Methods • EXTEND a method that takes no formal parameter and extends space for one new element. • EXTEND(n) a method that takes one formal parameter, which designates how many spaces to extend the collection. • EXTEND(n,m) a method that takes two formal parameters; the first designates how many spaces to extend, and the second identifies an index to copy into the newly indexed spaces. • FIRST a method that takes no formal parameter and returns the first index value, this is the lowest number for numeric indexes and lowest value string for string indexes. • LAST a method that takes no formal parameter and returns the last index value by using opposite rules to the FIRST method. Oracle Database PL/SQL 10g Programming (Chapter 6)

  19. CollectionsCOLLECTION API: Methods • LIMIT a method that returns the highest allowed element number in a VARRAY collection. • NEXT(n) a method that takes a single formal parameter that is an index value, and it returns the next value in the collection. • PRIOR(n) a method that takes a single formal parameter that is an index value, and returns the prior indexed value in the collection. • TRIM a method that takes no formal parameter, and removes the highest subscripted value from a collection. • TRIM(n) a method that takes one formal parameter, which is an INTEGER; and it removes that number of subscripted values from the end of a collection. Oracle Database PL/SQL 10g Programming (Chapter 6)

  20. CollectionsCOLLECTION API: Exceptions • COLLECTION_IS_NULL • Raised when attempting to access a null collection. • NO_DATA_FOUND • Raised when attempting to access values that are not present in an initialized collection. • SUBSCRIPT_BEYOND_COUNT • Raised when attempting to access beyond the highest subscripted value. • SUBSCRIPT_OUTSIDE_LIMIT • Raised when attempting to access beyond a VARRAY index value limit. • VALUE_ERROR • Raised when attempting to cast an incorrect data type to the index type of the subscript. Oracle Database PL/SQL 10g Programming (Chapter 6)

  21. Summary • Collection Types • VARRAY Collections • Nested Table Collections • Associative Array Collections • Collection API Oracle Database PL/SQL 10g Programming (Chapter 6)

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