A detailed explanation of MySQL operation in PHP

Next to bring you a few days to learn PHP and mysql some knowledge, very practical and very specific, covering all common PHP in the built-in method of MySQL.

Database connection:

mysql_connect (' localhost ', ' root ', ' root ');// three parameters are database address, database user name and password, respectively

Set the MySQL link identifier $con =mysql_connect (' localhost ', ' root ', ' root ')

Close the database by $con :mysql_close ($con);

Open a database:mysql_select_db ("database")// parameter is the name of the database to select

Executes an SQL statement:mysql_query (' insert into test (name) VALUES ("abc") ');

by printing mysql_error (); easy to see where an error occurred

mysql_query (' Set names UTF8 '); tell the database that the operations are UTF8 encoded format input and output

Mysql_fetch_row () fetching data as an indexed array

$query = mysql_query (' SELECT * from test ');// successful return of resource identifier (the address where the data returned by the statement is executed)

Mysql_fetch_row ($query);// Returns an array that displays information about the first data queried

If you want to output all the data that you have queried,

while ($row = Mysql_fetch_row ($query)) {Print_r ($row);} loop Print all queries to the information (an array of one array to print)

Thatmysql_fetch_row ()each time it executes, it takes one piece of data from the result set at a time. The index value of each array is related to the order of the fields. For example, a data hasname,Sex,Passwordfields, thearray[0]=>Shownamevalues, and so on. Therefore, the above statement can be passed directly through the$row [0]Getnameand so on.

Mysql_fetch_array () getting data in a mixed array form

$arr = Mysql_fetch_array ($query); After this is used, $attr [' name '] you can take it directly . name the value of the field

$arr = Mysql_fetch_array ($query, MYSQL_ASSOC); This will eliminate those arrays of indexed values, leaving only the part of the corresponding field name.

MYSQL_ASSOC: Returns an associative array (returns only an array of associated fields)

Mysql_num: Returns an array of numbers ( as mysql_fetch_row returns)

Mysql_both: Returning a mixed array

MYSQL_FETCH_ASSOC () An associative array form to get an array

Mysql_fetch_object () fetching and displaying data as an object

How to take a value:

$arr = Mysql_fetch_object ($query);

$arr, name; can be taken to name the value

Mysql_num_rows (): Gets the number of rows in the result set, returning a number. Can be used for data output before the judgment (with the if statement, no data when the output, save resources)

Mysql_result (); returns the value of a field in the result set

Mysql_result ($query, 0,1);// The second parameter specifies the number of rows to be taken, and the third Uncle specifies the field (offset) of the first. This way, the value of selecting a field is implemented.

Mysql_affected_rows: Gets the number of rows of the record affected by the previous operation (that is, several lines have been modified)

A detailed explanation of MySQL operation in PHP