Merge and truncate in sql, PL-SQL Programming

Assignment Help:

MERGE and TRUNCATE in SQL

SQL has two more table update operators, MERGE and TRUNCATE. MERGE, like INSERT, takes a source table s and uses it to update a target table t. Briefly, a MERGE statement specifies a matching condition to determine which rows of s have at least one matching row in t (under that specified matching condition). It then specifies an open-ended series of conditions to be applied to each row of s paired with actions to be applied on t.

WHEN MATCHED AND c1 THEN x1 specifies that action x1, necessarily an UPDATE or DELETE, is to be applied on t for each matching row in s that satisfies the condition c1. WHEN NOT MATCHED AND c2 THEN x2 specifies that action x2, necessarily an INSERT, is to be applied on t for each non-matching row in s that satisfies the condition c2. The curiously named TRUNCATE statement deletes all the rows from its specified target, bypassing any triggered actions, including compensatory actions, specified for that target. The target must be a base table.


Related Discussions:- Merge and truncate in sql

How pl/sql resolves the calls? , How Calls Are Resolved? The figure sho...

How Calls Are Resolved? The figure shows that how the PL/SQL compiler resolves the subprogram calls. When the compiler encounters the procedure or function call, it tries to di

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

I need simple hosted sql database, Project Description: I want a small r...

Project Description: I want a small relational database to be built. I want the database to have the subsequent information tables: Employee Information Document storage

Laws / rules associated with evolution, LAWS / RULES - Dollo's Law    ...

LAWS / RULES - Dollo's Law                     :           Living organisms do exhibit evolutionary irreversibility or evolution is irreversible. Williston's Law

Seeking a programmer to design a legal document, Seeking a programmer to de...

Seeking a programmer to design a legal document with pre-existing fields that could allow the auto-population of client(s) information (i.e. Name, Account Number, Address etc.) int

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

Third Step at defining type SID in SQL CREATE DOMAIN SID AS VARCHAR(5) CHECK ( VALUE IS NOT NULL AND SUBSTRING(VALUE FROM 1 FOR 1) = 'S' AND CAST('+'||SUBSTRING(VALUE

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

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

Package dbms output in pl/sql, DBMS_OUTPUT: The Package DBMS_OUTPUT en...

DBMS_OUTPUT: The Package DBMS_OUTPUT enables you to display output from the PL/SQL subprograms and blocks, that makes it easier to test and debug them. The procedure put_ line

Multiple assignment - sql, Multiple Assignment- SQL SQL supports mult...

Multiple Assignment- SQL SQL supports multiple assignment to local variables and also applies multiple assignment semantics in SET clauses of UPDATE statements, but does not

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