Nested tables versus index-by tables, PL-SQL Programming

Assignment Help:

Nested Tables versus Index-by Tables

The Index-by tables and nested tables are just similar. For e.g.  They have similar structure and their individual elements are accessed in the similar way (by using subscript notation). The main distinction is that the nested tables can be stored in a database column (and hence the word "nested table") while the index-by tables cannot.

The Nested tables extend the functionality of the index-by tables by letting you SELECT,
INSERT, DELETE, and UPDATE nested tables stored in the database. (Keep in mind, that index-by tables cannot be stored in the database). Some collection methods also operate only on the nested tables and varrays. For example, the built-in procedure TRIM cannot be applied to the index-by tables.

Another merit of the nested tables is that an uninitialized nested table is automatically null (that is, the table itself is null, not its elements), while an uninitialized index-by table is simply empty. Therefore, you can apply the IS NULL comparison operator to the nested tables but not to index-by tables.

Though, index-by tables also have some merits. For example, the PL/SQL supports implicit (automatic) datatype conversion between the host arrays and index-by tables (but not nested tables). Therefore, the most efficient way to pass collections to and from the database server is to use the anonymous PL/SQL blocks to bulk-bind input and output host arrays to the index-by tables.


Related Discussions:- Nested tables versus index-by tables

Rephrase conditional control statements, Rephrase Conditional Control State...

Rephrase Conditional Control Statements When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops evaluating the expression as s

Row counterparts of table operators - sql, Row Counterparts of Table Operat...

Row Counterparts of Table Operators SQL does not have counterparts tuple rename, tuple projection, tuple extension, tuple join and tuple compose. To obtain the same effects as

Using limit - collection method, Using LIMIT For nested tables, that h...

Using LIMIT For nested tables, that have no maximum size, the LIMIT returns NULL. For varrays, the LIMIT returns the maximum number of elements that a varray can have (that yo

Example of shorthand for a row constraint - sql, Example of Shorthand for a...

Example of Shorthand for a row constraint Example: Shorthand for a row constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Mark_in_range CHECK (Mark BETWEEN 0 AND 100);

Collection methods in pl sql, Collection Methods:   The collection me...

Collection Methods:   The collection method is a built-in function or procedure which operates on the collections and is called using the dot notation. The methods like the C

Initializing records, Initializing Records The illustration below show...

Initializing Records The illustration below shows that you can initialize a record in its type definition. Whenever you declare a record of the type TimeRec, its 3 fields supp

Functions - syntax, Functions The function is a subprogram which can ta...

Functions The function is a subprogram which can take parameters and be invoked. Normally, you can use a function to calculate a value. The function has 2 sections: the specifi

Example of table literal - sql, Example of Table Literal - SQL Exampl...

Example of Table Literal - SQL Example: A Table Literal (correct version) VALUES ('S1', 'C1', 'Anne'), ('S1', 'C2', 'Anne'), ('S2', 'C1', 'Boris'), ('S3', 'C3'

Table literals - sql, Table Literals - SQL One might expect SQL to sup...

Table Literals - SQL One might expect SQL to support table literals in the manner illustrated in Example 2.2, but in fact that is not a legal SQL expression. Example: Not a

Assignment of variable - updating a variable, Assignment of Variable - Upda...

Assignment of Variable - Updating a Variable Syntax: SET SN = SID ('S2'); This can obviously be read as "set the variable SN to be equal in value to SID ( 'S2' )".

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd