Effect of anonymous columns, PL-SQL Programming

Assignment Help:

Effect of Anonymous Columns

Now, recall that a VALUES expression denotes a table with undefined column names. If an initial value is to be specified when a base table is created, column definitions have to be implied by that initial value, so the question arises, how can a VALUES expression provide the initial value for a base table? The answer is that you have to learn an extra syntactic construct for that purpose, shown in Example.

Example: Specifying an initial value for a base table.

CREATE TABLE ENROLMENT (StudentId, Name, CourseId)

AS (VALUES (SID ('S1'), 'Anne', CID ('C1')),

(SID ('S2'), 'Boris', CID ('C1')))

WITH DATA;

Explanation:

(StudentId, Name, CourseId) provides the names, positionally corresponding to the anonymous columns of the AS table.
WITH DATA specifies that the given table is indeed to be the initial value. Curiously, this is required, unless WITHOUT DATA is written instead, in which case the AS table serves only to determine the declared types of the columns of the base table.
SQL does not allow constraints to be declared if AS is used in place of explicit column definitions.

Related Discussions:- Effect of anonymous columns

Using exception_init - user-defined exceptions, Using EXCEPTION_INIT T...

Using EXCEPTION_INIT To handle unnamed internal exceptions, you should use the OTHERS handler or the pragma EXCEPTION_INIT. The pragma is a compiler directive that can be th

Use native dynamic sql - improve performance of application, Use Native Dyn...

Use Native Dynamic SQL A few programs (a normal-purpose report writer for illustration) should build and process a variety of SQL statements at run time. Therefore, their full

Cursor attributes in dynamic sql - pl sql, Using Cursor Attributes: Ev...

Using Cursor Attributes: Every cursor has 4 attributes: %NOTFOUND, %FOUND, %ISOPEN, and %ROWCOUNT. If appended to the cursor name, they return the helpful information about

Relational algebra, Define basic operators of relational algebra with an ex...

Define basic operators of relational algebra with an example each

PROCEDURE, Create a procedure named DDPROJ_SP that retrieves project inform...

Create a procedure named DDPROJ_SP that retrieves project information for a specific project based on a project ID. The procedure should have two parameters: one to accept a projec

Grouping and ungrouping in sql, Grouping and Ungrouping in SQL Example...

Grouping and Ungrouping in SQL Example specifying EXAM_MARK in place of COURSE in the main FROM clause. Example: Obtaining C_ER2 from EXAM_MARK SELECT CourseId, CAST

Using operator ref - manipulating objects pl sql, Using Operator REF: ...

Using Operator REF: You can retrieve refs by using the operator REF that, like VALUE, takes as its argument a correlation variable. In the illustration below, you retrieve one

Null statement-sequential control, NULL Statement The NULL statement c...

NULL Statement The NULL statement clearly specifies in action; it does nothing other than to pass control to the next statement. It can, though, improve the readability. In a

Use of table comparisons - sql, Use of Table Comparisons - SQL Table ...

Use of Table Comparisons - SQL Table comparisons where it is noted that although table expressions cannot be compared, we have TABLE (t) to convert a table expression t into

Example of not exists operator - sql, Example of NOT EXISTS Operator - SQL ...

Example of NOT EXISTS Operator - SQL Example is a translation into SQL of the corresponding example, which is included there merely to show that for any scalar comparison the

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages