Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Row Counterparts of Table Operators
SQL does not have counterparts tuple rename, tuple projection, tuple extension, tuple join and tuple compose. To obtain the same effects as these operators on row r, one has first to derive the table t consisting of just r, then apply the SQL counterpart of the corresponding relational operator on t, putting parentheses around the table expression so that, so long as the context is appropriate, it becomes a row subquery. For example, if r has fields named a, b, and c, we can simulate a tuple renaming of a tuple projection to obtain the row consisting of just a and b, with b renamed to x, by (SELECT a, x FROM VALUES (r) AS t(a, x, c)).
The snag here is that the columns of a VALUES expression have implementation-dependent names, so we cannot rely on the field names of r being propagated to the table. We therefore have to specify the names in parentheses after the range variable name, t. At least that gives us the slight short cut of renaming b as x on the fly, so to speak.
Using NOT NULL Besides assigning an initial value, the declarations can impose the NOT NULL constraint, as the example below shows: acct_id INTEGER(4) NOT NULL := 9999; You ca
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
What are the rates for help in writing PL/SQL procedures and functions?
Use Bulk Binds If SQL statements execute inside a loop using the collection elements as bind variables, context switching between the PL/SQL & SQL engines can slow down the ex
Stored Subprograms Normally, tools (like Oracle Forms) which incorporate the PL/SQL engine can store subprograms locally for later, strictly local execution. Though, to become
Processing Transactions This part describes how to do the transaction processing. You learn the fundamental techniques that safeguard the consistency of your database, involvin
Closing a Cursor The CLOSE statements disable the cursor, and the result set becomes undefined. An illustration of the CLOSE statement as shown: CLOSE c1;
What Is a Package? The package is a schema object that group logically related PL/SQL items, types, and subprograms. The Packages usually have 2 parts, a specification & a bo
Set Operators The Set operators combine the results of the two queries into one result. The INTERSECT returns all the distinct rows selected by both queries. The MINUS returns
Using FIRST and LAST FIRST and LAST return the first and last (minimum and maximum) index numbers in a collection. When the collection is empty, the FIRST and LAST return NULL
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd