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.
Identifiers You use identifiers to name the PL/SQL program items and units that include constants, variables, cursors, exceptions, cursor variables, subprograms, and packages.
Scope and Visibility The References to an identifier are resolved according to its visibility and scope. The scope of an identifier is that area of a program unit (subprogram, b
Iteration Schemes The bounds of a loop range can be variables, literals, variables, or expressions but must compute to integers. Below are some of the examples. As you can see t
Sequential Control Dissimilar to the IF and LOOP statements, the GOTO and NULL statements are not important to the PL/SQL programming. The configuration of PL/SQL is such that th
SQL Functions The PL/SQL uses all the SQL functions involving the following aggregate functions that summarize the whole columns of the Oracle data: GROUPING, AVG, COUNT, STDDE
Substitution and Instantiation - SQL It shows how NULL might appear in substitution for a parameter of a predicate and how it might thus participate in instantiation of that p
COSMOZOI C THEORY - Richter (1865) proposed the cosmozoic theory that says that life came by spores (cosmozoa) or other particles from other planets on the earth.
Rephrase Conditional Control Statements When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops evaluating the expression as s
Indeterminacy in SQL Some SQL expressions are actually not function invocations at all in the mathematical sense, being indeterminate-invocations operating on identical input
Ending Transactions A good quality programming practice is to commit or roll back every transaction explicitly. Whether you rollback or issue the commit in your PL/SQL program
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