Several common database operation functions in MySQL

Some commonly used MySQL operation functions, and the MySQL operation is closely related, I believe that the development of PHP's primary enthusiasts will be a great help.

1.mysql_connect--open a link to the MySQL server

Description: The link is closed after the page execution completes.

Example:

$link = mysql_connect ("localhost", "root", "") or Die ("Could not connect:". Mysql_error ());

2.mysql_close--close MySQL Link

function form: bool Mysql_close ([Resource link_identifier])

Description: Link_identifier closes the last open Non-persistent link by default.

Example:

$link = Myql_connect ("localhost", "root", "") or Die ("Link failed! Error message:". Mysql_error ());

echo "link Success";

Mysql_close ($link);?

3.mysql_pconnect--open an execution link to the MySQL server

Description: Similar to the mysql_connect, only established is a persistent link, more commonly used and convenient.

Example:

$link = Mysql_pconnect ("localhost", "root", "") or Die ("Could not connect:". Mysql_error ());

4.mysql_select_db--Choose MySQL Database

function form: bool mysql_select_db (string Database_name,resource link_identifier)

Note: Once the link is successful, you should immediately use this function to specify a database for the link identity.

Example:

$link = Myql_connect ("localhost", "root", "") or Die ("Link failed! Error message:". Mysql_error ()); echo "Link succeeded";

mysql_select_db ("Example", $link) or die (' cannot use example library ');

mysql_query ("INSERT into users (name) VALUES (' John ')");

Mysql_close ($link);

5.mysql_query--send a MySQL statement

Description: This is the most commonly used function, almost all SQL statements and MySQL-specific commands are executed through it.

Function form: Resource mysql_query (String Query,resource link_identifier)

Example:

$result = mysql_query ("SELECT * from users");

6.mysql_num_rows--the number of rows in the result set

function form: int mysql_rows (resource result)

Note: Gets the number of record bars for the result set, only valid for the result set returned by the Select. If it is the result of Update/insert, choose to use the Mysql_affected_rows function to get the number of records affected.

Example:

$result = My sample Sql_query ("SELECT * from users", $link);

$num _rows = mysql_num_rows ($result);

echo "Found it". $num _rows. " Record n ";

7.mysql_affected_rows--the number of record rows affected by the previous MySQL operation

function form: int mysql_affected_rows (Resource link_identifier)

Note: This function should be executed immediately after executing the mysql_query function of the corresponding SQL

Example:

mysql_query ("DELETE from users WHERE ID < 10");

echo "This operation has been removed". Mysql_affected_rows (). Line Record ";

8.mysql_error--returns the text error message from the previous MySQL operation

function form: String mysql_error (Resource Link_identifier)

Description: It returns the text message for the last time MySQL error occurred

9.mysql_insert_id--gets the ID generated by the previous insert operation

function form: int mysql_insert_id (Resource link_identifier)

Description: The primary key value that MySQL automatically generates when it gets the most recent insert operation

Example:

mysql_query ("INSERT into users (name) values (' Kossu ')");

Echo ("ID of last insert operation". mysql_insert_id ());

10.mysql_fetch_array--takes one row from the result set as an associative array, or an array of numbers, or both

function form: Array mysql_fetch_array (Resource Result,int result_type)

Description: Takes a record from the result set and moves it down a cursor, which makes it possible to access the target data through the array.

Parameter description: Result: Results set by mysql_query function query.

Result_type: Can only be Mysql_assoc, Mysql_num, Mysql_both, the return array index form. Default is Mysql_both.

Example:

$result = mysql_query ("SELECT id,name from Users");

while ($row = Mysql_fectch_array ($result))

{

echo "id=". $row [0]. "; Name= ". $row [" name "]."

";

}

Referring to these functions, you can write a MySQL operation class based on PHP, which includes the functions of connecting to MySQL, closing links, deleting data, modifying and adding content.