Update command- sql, PL-SQL Programming

Assignment Help:

UPDATE Command- SQL

Loosely speaking, UPDATE changes some of the column values of some existing rows of its target table. Thus, although some rows disappear from the target and others arrive in it, so to speak, the cardinality of the table does not change. Suppose the exam board for course C2 decides that the exam has been marked too harshly and everybody's mark is to be increased by 5. Example shows how.

Example: Adding 5 to all the marks for course C2

UPDATE EXAM_MARK SET Mark = Mark + 5

WHERE CourseId = 'C2';

The syntax is self-explanatory. The WHERE specification is optional and defaults to WHERE TRUE, meaning that the specified changes are to be applied to all existing rows in the target table. The expression Mark = Mark + 5 is a column assignment. When several column assignments are needed they are separated by commas and the semantics of multiple assignment as described in the theory book apply: the right-hand sides are all evaluated before any column assignments are performed. The same column cannot be the target or more than one assignment.


Related Discussions:- Update command- sql

Implicit cursors, Implicit Cursors The Oracle implicitly opens a curso...

Implicit Cursors The Oracle implicitly opens a cursor to process each SQL statement not related with an explicitly declared cursor. The PL/SQL lets you refer to the most recen

Table represents an extension - sql, Table Represents an Extension - SQL ...

Table Represents an Extension - SQL It describes how each tuple in a relation represents a true instantiation of some predicate and each true instantiation is represented by s

Example of except operator - sql, Example of EXCEPT Operator - SQL Ex...

Example of EXCEPT Operator - SQL Example, like its counterpart in the theory book, illustrates the convenience of allowing any table expression to be the source for an INSERT

Cursor variables in pl sql, Cursor Variables:   To execute the multi-...

Cursor Variables:   To execute the multi-row query, the Oracle opens an unnamed work region that stores the processing information. You can use an explicit cursor that names

Using delete - collection method, Using DELETE This process has three ...

Using DELETE This process has three forms. The DELETE removes all elements from the collection. DELETE(n) removes the nth element from the nested table. When n is null, then D

Sql is a database language, SQL Is a Database Language: The commands g...

SQL Is a Database Language: The commands given to a DBMS by an application are written in the database language of the DBMS. The term data sublanguage is sometimes used instea

Inner join, Inner Join We have learned how to retrieve data from one t...

Inner Join We have learned how to retrieve data from one table by using SELECT statement. But, as we have learned, normalized relational databases mean the data is spread betw

Theory of spontaneous generation - origin of life, THEORY OF SPONTANEOUS GE...

THEORY OF SPONTANEOUS GENERATION - ABIOGENESIS OR AUTOGENESIS - According to this theory, the existing living communities have originated from non-living organic matter with

Procedural constraint enforcement (triggers) , Procedural Constraint Enforc...

Procedural Constraint Enforcement (Triggers) SQL has an alternative method of addressing database integrity, involving event-driven procedural code. The special procedures th

Cursor variables as parameters, Cursor Variables As Parameters You can...

Cursor Variables As Parameters You can declare the cursor variables as the formal parameters of the functions and procedures. In the illustration below, you define the REF CUR

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