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.

Posted Date: 1/18/2013 11:38:21 PM | Location : United States

Ask an Expert

Related Discussions:- Update command- sql, Assignment Help, Ask Question on Update command- sql, Get Answer, Expert's Help, Update command- sql Discussions

Write discussion on Update command- sql
Your posts are moderated

Write your message here..

Related Questions

Role of abstraction in pl/sql, Role of Abstraction in pl/sql: The abst... Role of Abstraction in pl/sql: The abstraction is a high-level description or model of a real-world entity. The Abstractions keep our daily lives convenient. They help us ca

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 queries-oracle , 1- You can check attribute names from each table in D... 1- You can check attribute names from each table in DBF11 by running for example:  desc dbf11.Member;  desc dbf11.Agent;  desc dbf11.Producer; Because some attribute names in

Tables within a table - sql, Tables within a Table - SQL Figure here ... Tables within a Table - SQL Figure here is an exact copy of the one in the theory book and as before it is just an alternative way of representing some of the information con

Perform exception handling with user-defined errors, On occasion, some of B... On occasion, some of Brewbean's customers mistakenly leave an item out of a basket already checked out, so they create a new basket containing the missing items. However, they requ

Semidifference via except and join - sql, Semidifference via EXCEPT and JOI... Semidifference via EXCEPT and JOIN - SQL SELECT * FROM (SELECT StudentId FROM IS_CALLED WHERE Name = 'Devinder' EXCEPT DISTINCT CORRESPONDING SELECT StudentId

Controlling cursor variables, Controlling Cursor Variables You use 3 s... Controlling Cursor Variables You use 3 statements to control the cursor variable: OPEN-FOR, FETCH, & CLOSE. At First, you OPEN a cursor variable FOR a multi-row query. Then, y

Manipulating local collections - pl/sql, Manipulating Local Collections ... Manipulating Local Collections Within PL/SQL, to manipulate the local collection, by using the  TABLE and CAST operators . The operands of CAST are a collection declared locally

Referencing records, Referencing Records Unlike the elements in a coll... Referencing Records Unlike the elements in a collection, that are accessed using subscripts, the fields in a record are accessed by name. To reference an individual field, you

Difference between implicit and explicit cursor, Implicit Cursor is declare... Implicit Cursor is declared and used by the oracle environment internally. while the explicit cursor is declared and used by the external user. more over implicitly cursors are no