Oracle has also included several smaller PL/SQL enhancements and the following features are briefly covered in this article: simplified sequence expressions; named notation support in SQL; CONTINUE statement; SIMPLE. As most developers will be aware, sequences have never been directly supported in PL/SQL.

In versions prior to 1. In 1. 1g, however, Oracle has added sequence fetching (using NEXTVAL and CURRVAL) to the list of valid PL/SQL expressions. This means we can use sequence expressions in PL/SQL anywhere we can validly use a number. To demonstrate this, we will create a sequence (.

Note that we can also use CURRVAL in the same manner as NEXTVAL, as the following example demonstrates. Oracle's underlying implementation of sequences and sequence- fetching hasn't changed, as we will now demonstrate. In the following example, we will use SQL trace to compare the performance of sequence assignment expressions with the pre- 1. DUAL table. We will execute 1. Note how we alias the pseudo- column as . LOOP. 5 n : = s. NEXTVAL. 6 END LOOP.

Reference partitioning is a new partitioning option in Oracle 11g that allows the partitioning of two related tables to be based. Overview of Triggers. A trigger is a named program unit that is stored in the database and fired (executed) in response to a specified event. The specified event is. 1.1.1 APIs and Precompilers. The following sections describe new Oracle Database 11 g features in application programmatic interfaces. These features improve.

FOR i IN 1 . 1. 00. LOOP. 8 SELECT s. NEXTVAL AS nval INTO n FROM dual.

END LOOP. PL/SQL procedure successfully completed. As stated, Oracle's implementation of sequence fetching hasn't changed. The new PL/SQL sequence expression is executed . The first entry is as follows. Oracle updated the SEQ$ table 5. This is the statement that Oracle executed to support our new sequence expression.

We know this because there is no . How To Install Screw On Exhaust Tips there. We can see that the statistics for I/O, executes and fetches are identical to those for our 1. PL/SQL sequence expressions. Critically, the elapsed and CPU times are also the same (we attribute such tiny differences to .

We conclude, therefore, that the new sequence syntax provides greater convenience, but nothing else. Continuing with the theme of convenience, Oracle 1. SQL calls to PL/SQL functions.

This is technically a SQL enhancement, but as it relates directly to PL/SQL invocation, it is included in this article. Named notation has been a PL/SQL- only feature for many years and versions. With named notation, we are able to supply parameters to functions and procedures by name as well as position, using syntax such as the following. Similarly, they can be mixed with positional notation if required (a good example of this is DBMS.

Named notation enables us to skip non- mandatory parameters that we do not need to change or supply, so can be very convenient when calling procedures with long lists of defaults. As stated, we can now use named notation in SQL and we will see some examples below. We will begin by creating a function with three default parameters, as follows. In the following example, we will supply the first and third parameters only. We can call Oracle's packaged functions with named notation, as follows. These functions are defined in the STANDARD package (function UPPER(ch VARCHAR2 CHARACTER SET ANY. As an aside, 1. 1g includes a new pair of views, V$SQLFN.

For example, we can get the signature of the UPPER function as follows (note that we've used Tom Kyte's print. It isn't necessarily good practice to have overloaded functions with the same type signatures, but nevertheless, named notation makes it possible (remember that it is possible in PL/SQL prior to 1. SQL). To demonstrate this, we will create the simplest example of overloaded functions that share the same type signatures, as follows. We will create the package body with trivial implementations for these functions, as follows. Oracle cannot possibly know which of the versions we wish to call.

Overloads commonly have different signatures (i. In these cases, positional notation is usually sufficient. In 1. 1g (or PL/SQL in earlier versions of course), this issue disappears, because we can use named notation, as follows. For completeness, we will call the alternative version of this overload, as follows. PL/SQL has supported the GOTO and EXIT statements for many years, but in 1. Oracle has added the CONTINUE statement. This statement enables us to terminate the current iteration of a loop and return to the start of the next cycle.

The easiest way to understand the CONTINUE statement is by example. We will begin by coding a simple FOR loop with five iterations. At the end of each iteration we will output a message, but on the even- numbered iterations, we will skip to the start of the next iteration. LOOP. 3 IF i IN (2,4) THEN. CONTINUE. 5 END IF. DBMS. The even- numbered iterations returned to the start of the loop for the next iteration. Note that this example used an IF statement to test the iteration numbers, but the new CONTINUE statement has a WHEN condition for this purpose, as follows.

LOOP. 3 CONTINUE WHEN i IN (2,4). DBMS. 5 LOOP. 4 CONTINUE main.

In the following example, we will create two simple FOR loops. We will label them .

LOOP. 5 DBMS. 5 LOOP. CONTINUE main. It is a subtype of PLS.

Where raw performance is of critical importance (and the two restrictions of SIMPLE. Best Software For Molecular Modeling Kit. Note that the 1. 0g types, BINARY. We will concentrate on SIMPLE. This means we must initialise all variables, otherwise Oracle will raise an exception, as follows. We will create a small procedure with a single parameter of SIMPLE.

In the following example, we will attempt to pass a NULL value for the parameter. Similarly, we cannot define a NULL default value for this parameter, as the following demonstrates. We will lookup the errors for our procedure, as follows. We will see how below. First, the basic integer range for SIMPLE. In the following example, we will start with an integer value at the upper limit of the integer range and increment it by one.

When we reach the upper limit of a SIMPLE. The opposite is true if we subtract from the lower limit of the integer, as in the following example. Note that in both scenarios, using a PLS. We can run some basic performance comparisons to test out this claim. In the following example, we will run a .

For each execution of the test, we will loop a given number of times and output the time taken. The test harness is as follows. LOOP. 1. 1 s : = s + 1. END LOOP. 1. 3 timer.

SIMPLE. 1. 0 ** n LOOP. END LOOP. 1. 9 timer. PLS. We will begin with one million iterations, as follows. We will repeat the test using an order of magnitude more loop iterations, as follows.

At this point, most developers will realise that the SIMPLE. Finally, we will test with one thousand million iterations (a billion to some), as follows.

Note, however, that using SIMPLE. For raw speed, therefore, SIMPLE. It enables us to compile our PL/SQL programs directly as C, rather than as interpreted . It is typically faster for computationally intensive programs (rather than those with a large proportion of work done by SQL). Oracle 1. 1g simplifies the way in which we can make use of native compilation (many developers will be aware of the setup difficulties in earlier versions of the database).

It does this by shipping with a built- in C- compiler (many servers do not have C- compilers due to either cost or security) and reducing the setup needed such that it works . We will see examples of this below. To test native compilation, we will continue with the SIMPLE.

We will first create a package to store these tests, as follows. To have all packages natively compiled by default, this can be set to . In this example, we will be controlling the compilation mode at package level. We will now create our package body, as follows. LOOP. 8 s : = s + 1.

END LOOP. 1. 0 timer. LOOP. 1. 8 p : = p + 1. END LOOP. 2. 0 timer. We can check the compilation mode of our test package in the USER. In this case, we have simply confirmed that our test package is compiled in interpreted mode. We will execute it in this mode to give us a baseline, as follows.

We will now compare this with native compilation. First we will recompile our package natively, as follows. No setup has been required on this 1. This will encourage more developers to make use of this feature (where it is applicable).