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Excel-DB Oracle Database Tips by Donald Burleson

Basics

PHP is an interpreted scripting language embedded in HTML pages and executed by the web server or on the command line. Apache, IIS, and other web servers can execute PHP if the proper options are selected during the installation. Installation of PHP is not covered in this book. To obtain an accurate and complete guide for this installation, access:  http://www.php.net

As in any other programming language, PHP consists of expressions connected by operators and handled by commands. Operators are more or less the same as in the other scripting languages. Operator tables have been taken from the PHP on-line manual in their original format and are listed on the next two pages.

 ASSOCIATIVELY OPERATORS Non-associative New Right [ Non-associative ++-- Non-associative ! ~ - (int) (float) (string) (array) (object) @ Left * / % Left +-. Left << >> Non-associative < <= > >= Non-associative == != === !== Left & Left ^ Left | Left && Left || Left ?: Right = += -= *= /= .= %= &= |= ^= <<= >>= Left And Left Xor Left Or Left ,

Table 1.1: Operator Precedence

 EXAMPLE NAME RESULT -\$a Negation Opposite of \$a. \$a + \$b Addition Sum of \$a and \$b. \$a - \$b Subtraction Difference of \$a and \$b. \$a * \$b Multiplication Product of \$a and \$b. \$a / \$b Division Quotient of \$a and \$b. \$a % \$b Modulus Remainder of \$a divided by \$b.

Table 1.2: Arithmetic Operators

 EXAMPLE NAME RESULT \$a == \$b Equal TRUE if \$a is equal to \$b. \$a === \$b Identical TRUE if \$a is equal to \$b, and they are of the same type. (introduced in PHP 4) \$a != \$b Not equal TRUE if \$a is not equal to \$b. \$a <> \$b Not equal TRUE if \$a is not equal to \$b. \$a !== \$b Not identical TRUE if \$a is not equal to \$b, or they are not of the same type. (introduced in PHP 4) \$a < \$b Less than TRUE if \$a is strictly less than \$b. \$a > \$b Greater than TRUE if \$a is strictly greater than \$b. \$a <= \$b Less than or equal to TRUE if \$a is less than or equal to \$b. \$a >= \$b Greater than or equal to TRUE if \$a is greater than or equal to \$b.

Table 1.3: Comparison Operators

 Example Name Result \$a and \$b And TRUE if both \$a and \$b are TRUE. \$a or \$b Or TRUE if either \$a or \$b is TRUE. \$a xor \$b Xor TRUE if either \$a or \$b is TRUE, but not both. ! \$a Not TRUE if \$a is not TRUE. \$a && \$b And TRUE if both \$a and \$b are TRUE. \$a || \$b Or TRUE if either \$a or \$b is TRUE.

Table 1.4: Logical Operators

There is only one operator that can be regarded as a string operator: "." (dot) represents concatenation as in the following example:

\$a="Using PHP ";
\$b="with Oracle";
\$c=\$a.\$b;

The value of the variable \$c is "Using PHP with Oracle".

PHP variables can be numeric or textual scalars, arrays indexed by numbers, associative arrays (also known as "hashes") and objects. All variables are prefixed by the dollar sign "\$". There is no distinction between arrays, hashes and scalars based on the prefix, such as in Perl in which those are marked by @,% and \$ respectively.

As in Perl, alphanumeric characters and underscore (_) characters are allowed in the variable names. Variables are weakly typed, meaning that the type cannot be declared. It is perfectly acceptable to assign a string to the numeric variable, or vice versa.

Generally speaking, PHP distinguishes between lowercase letters and uppercase letters. However, there are exceptions which will be pointed out as they are encountered.  Again, PHP is embedded into HTML and can be mixed with HTML tags.  Web servers interpret everything between the <?php and ?> as a PHP routine and passes it to the PHP interpreter either embedded in the server itself or called as a CGI script.

The following contains a few examples of PHP variables:

\$a=5;
\$b="Hello World!";
\$c=array("a",5,3.14,"Hello World",NULL
);
\$d=TRUE;

See code depot for complete scripts

This is an excerpt from the book Easy Oracle PHP.  You can get it for more than 30% by buying it directly from the publisher and get instant HTML-DB scripts from the code depot: Easy Oracle PHP Create Dynamic Web Pages with Oracle Data Includes online HTML-DB code depot Buy it now for 30% off - Only \$19.95

HTML-DB support: For HTML-DB development support just call to gat an Oracle Certified professional for all HTML-DB development projects. ��         Burleson is the American Team Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

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