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

Sql, Write a query to find academics that are authors and that have only ev...

Write a query to find academics that are authors and that have only ever coauthored papers with authors from institutes in the same state as their own. List their academic number,

Wrapping and unwrapping in sql, Wrapping and unwrapping in SQL Operato...

Wrapping and unwrapping in SQL Operators WRAP and UNWRAP in connection with attributes whose declared types are tuple types. Example shows how extension and projection can be

First step at defining type sid in sql, First Step at defining type SID in ...

First Step at defining type SID in SQL CREATE TYPE SID AS ( C VARCHAR(5) ) ; Explanation: TYPE SID announces that a type named SID is being defined to the syst

In out mode - parameter modes, IN OUT Mode An IN OUT parameter passes ...

IN OUT Mode An IN OUT parameter passes initial values to the subprogram being called and return efficient values to the caller. Within the subprogram, an IN OUT parameter acts

Boolean values-assignments in pl/sql, Boolean Values Only the values TRU...

Boolean Values Only the values TRUE, FALSE, & NULL can be assigned to a Boolean variable. For illustration, given the declaration DECLARE done BOOLEAN; the following statements

"not enforced" table constraints - sql, "Not Enforced" Table Constraints ...

"Not Enforced" Table Constraints A constraint that is not enforced is not really a constraint within the meaning of the act, but SQL does have such a concept and it needs to b

Data types, Datatypes Every constant and variable has a datatype that s...

Datatypes Every constant and variable has a datatype that specifies the storage format, constraints, and the valid range of values. The PL/SQL gives a variety of predefined dat

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

Ssrs report writing, SSRS Report Writing Project Description: This re...

SSRS Report Writing Project Description: This report is part of a larger project to make a SQL Server Reporting Service (SSRS) based reporting solution. There can be more rep

Use of count in sql, Use of COUNT in SQL It describes and discusses va...

Use of COUNT in SQL It describes and discusses various general methods of expressing constraints, eventually noting that support for "=" with relation operands is sufficient f

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