This function returns the absolute (positive) value of
expr.
| ||
This function returns -1, 0, or 1 depending on whether
expr is negative, zero, or positive, respectively.
| ||
This function returns the remainder of dividing
expr1 by expr2.
| ||
This function rounds down expr. returns the
largest integer value that is less than or equal to
expr.
| ||
This function rounds up expr . returns the
smallest integer value that is greater than or equal to
expr.
| ||
This function returns expr rounded to the nearest
integer. Note that the behaviour when the value is exactly an integer plus 0.5
is system dependant. Thus, you should not rely on any particular outcome when
migrating to a new system.
| ||
This function rounds expr to a number with
num decimal places, leaving trailing zeroes in place. Use
num=2, for example, to format a number as dollars and cents. Note that
the same uncertainty about the rounding of 0.5 applies as discussed for
ROUND above.
| ||
This function returns eexpr, the base of
natural logarithms raised to the power of expr.
| ||
This function returns ln expr, or logarithm of expr.
Remember, a logarithm with an arbitrary base B can be
calculated as LOG(expr)/LOG(B).
| ||
This function returns the base-10 logarithm of
expr.
| ||
This function returns expr1 raised to the power of
expr2.
| ||
This function returns the square root of
expr.
| ||
This function returns the value of πpi.
| ||
This function returns the cosine of expr in radians
| ||
This function returns the sine of expr in radians
(e.g. SIN(PI()) = 0).
| ||
This function returns the tangent of expr in
radians (e.g. TAN(PI()) = 0).
| ||
This function returns the arc cosine (cos-1 or
inverse cosine) of expr (e.g. ACOS(-1) =
3.141593).
| ||
This function returns the arc sine (sin-1 or
inverse sine) of expr (e.g. ASIN(0) =
3.141593).
| ||
This function returns the arc tangent (tan-1 or
inverse tangent) of expr (e.g. ATAN(0) =
3.141593).
| ||
This function returns the angle (in radians) made at the
origin between the positive x axis and the point
(x,y) (e.g. ATAN(1,0) =
1.570796).
| ||
This function returns the cotangent of expr (e.g.
COT(PI()/2) = 0).
| ||
This function returns a random, floating point number
between 0.0 and 1.0. If expr is specified, a random number will be
generated based on that value, which will always be the
same.
| ||
This function returns the smallest of the values
specified.
| ||
This function returns the largest of the values
specified.
| ||
This function returns the value of expr (in
radians) in
degrees.
| ||
This function returns the value of expr (in
degrees) in radians.
| ||
This function returns the value of floating point number
expr truncated to num decimal places
|
shell%mysqldump -h myhost -u root -pmypass dbname > dbname_backup.sql
shell%mysqladmin -h myhost -u root -pmypass create dbname shell%mysql -h myhost -u root -pmypass dbname < dbname_backup.sql
Opens a file for reading and/or writing. This file can be
stored on the server's hard disk, or PHP can load it from a URL just like a Web
browser would.
| ||
Tells PHP you're finished reading/writing a particular file
and releases it for other programs or scripts to use.
| ||
Reads data from a file into a PHP variable. Allows you to
specify how much information (i.e. how many characters or bytes) to
read.
| ||
Writes data from a PHP variable into a
file.
| ||
Performs a run-of-the-mill file copy
operation.
| ||
Deletes a file from the hard disk.
Through examination of server logs, you'll probably find that this is one of the most requested pages on your site. If you ask yourself some of the questions above, you'll realize that this page doesn't have to be dynamically generated for every request. As long as it's updated every time new content is added to your site, it'll be as dynamic as it needs to be. With a PHP script, you can generate a static snapshot of the dynamic page's output and put this snapshot online, in place of the dynamic version . By converting high-traffic dynamic pages into semi-dynamic equivalents, which are static pages that get dynamically regenerated at regular intervals to freshen their content, you can go a long way towards reducing the toll that the database-driven components of your site take on your Web server's performance. Website, you probably see site traffic as something you'd like to encourage. Unfortunately, high site traffic is just the kind of thing that a Web server administrator dreads—especially when that site is primarily composed of dynamically generated, database-driven pages. Such pages take a great deal more horsepower from the computer that runs the Web server software than plain, old HTML files do, because every page request is like a miniature program that runs on that computer.
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