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!
Relational Algebra - SQL
It describes some operators, that together constitute an algebra that is not only relationally complete but also irreducibly so (very nearly- apart from RENAME, which can be expressed in terms of extension and projection, none of those operators can be discarded without sacrificing completeness). We can use these operators as a basis for testing SQL for relational completeness. If we can show that for every invocation of one of these operators there is an equivalent SQL expression, then we will have shown that SQL is relationally complete. By "equivalent" we mean an expression whose table operands are counterparts of the relation operands (ignoring the ordering that SQL imposes on the columns) and whose result is a table counterpart result, where a table is a counterpart of a relation if and only if it satisfies all of the following conditions:
Use of Table Comparisons - SQL Table comparisons where it is noted that although table expressions cannot be compared, we have TABLE (t) to convert a table expression t into
Special cases of projection This section describes the identity projection, r {ALL BUT}, and the projection on no attributes, r { }, which yields TABLE_DUM when r is empty, ot
Using Savepoints The scope of the savepoint is a transaction in which it is defined. The Savepoints defined in the major transaction are not related to the savepoints defined
Defining Autonomous Transactions To define an autonomous transaction, you use the pragma (compiler directive) AUTONOMOUS_TRANSACTION. The pragma instructs the PL/SQL compiler
At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a trigger that automatically updates the stock level of all pr
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
Description: Demonstrate your knowledge of PL/SQL programming by writing and thoroughly testing triggers and stored procedures associated with an e-commerce application that pr
Mutual Recursion The Subprograms are mutually recursive if they directly or indirectly call each other. In the illustration below, the Boolean functions odd & even, that dete
Understanding Nested Tables Within the database, the nested tables can be considered as one-column database tables. The Oracle stores the rows of a nested table in no specific o
FETCH Statement The FETCH statement retrieve rows of data one at a time from the result set of the multi-row query. The data is stored in fields or variables which correspond t
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