Knowledge Collection in PHP

I have not learned PHP before, just a project need to use recently, I decided to learn while doing PHP.

1 in the SQL statement you can add a restriction condition: Left (text,20) only the first 20 words of the text;

2 can be used as pagination using limit FromRecord, recordnum, for example, limit 0,30 indicates that 30 records are traversed from the first record;

The 32-table connection can be: Table1 join table2 using X (x is a common field for two tables), or table1 join table2 on table1.x = table2.x

4 PHP Access querystring can be used $page = $_get[' page '];

Or

$page = $_request[' page '];

Which request can obtain post,get,querystring and other characters;

Before that, I saw a more stupid way:

Parse_str ($_server[' query_string '), $output); First, save the query string into an array $output

$page = $output [' page ']; And then indexed by variable name

5 The comparison of date functions in PHP is actually a string comparison;

6 Date type data in MySQL can be: 2000-02-03,2002.02.03,2002.2.3,02.02.03,02.2.3, which means there must be a month and a day, and must be '-' or '. ' Apart.

7 data () to get the time zone problem, I found that the time is less than 8 hours, because php.ini inside the default configuration is GTM U.S. time zone;

WORKAROUND: You can modify the php.ini:

[Date]

; Defines the default timezone used by the date functions

Date.timezone = "Asia/shanghai"

Alternatively, use the date () function plus date_default_timezone_set ("PRC");

81 period of time, debugging in the body always said I was missing ")", the cost of a half-day is intval ($_post[' Consumetype '), the field in the database is varchar (50), in the Zengsong table I do not use the Intval function, Because its ID is 1,2 ... integers and char can convert to each other, but in the other two tables it's a5a,sp07-01, but how does it convert to int?

Let's look at the declaration of the Intval function:

The Intval function is used to get the integer value of the variable: int intval (mixed var [, int base])

Returns the integer value of the variable var by using a specific binary conversion (the default is decimal).

var can be any scalar type. Intval () cannot be used for array or object.

9 Another inexplicable problem, with user name 1 login can be, change a ' Bo ' Landing, the system is in place error: Said I run time error: Missing ""), Nnd. Check that the variable type in the SQL statement is inconsistent with the database,

In PHP when you convert from floating-point numbers to integers, the digits are rounded up (drop decimal places).

11 in the MySQL INSERT statement, if the self-added field is to be replaced with (NULL).

PHP in Chinese garbled??? Problem solving:

Adding mysql_query ("Set names ' gb2312") after mysql_connect;

Or the full use of UTF8 code, you do not have to add the above statement.

There are function Iconv ("GBK", "UTF8", "strings"), and various character encoding conversions can be implemented.