PHP's mysql extension arrangement and realizing the operation of the database analysis

To some extent, php is a database of customer end.

Although officials have not recommended, php7.0 even mysql extension has been removed, but to learn about the process-oriented programming ideas is good.

 

Core step

Connect to the database => execute sql statement

In fact, by extension mysql database operations are built around these two steps of

 

detailed steps

Detailed flow diagram of the steps of:

Query operation

The following procedure can be achieved queries the local test database class table and output results:

? < PHP
 header ( "Content-of the type: text / HTML; charset: UTF-8" );
 // The first step: connect to the database 
$ conn = @ mysql_connect ( 'localhost', 'root', 'root' );
 IF (! $ Conn ) {
     Die ( "connection failed, an error message." mysql_error ()); 
} 
// step: select database 
the mysql_select_db ( "Test" ); 

// third step: character set 
mysql_set_charset ( "utf8 " ); 

// step Four: create sql statement 
$ sql =" the SELECT * from `class`" ; 

// step five:Execute SQL 
IF ( $ RES = mysql_query( $ SQL )) {
     the while ( $ Row = mysql_fetch_assoc ( $ RES )) {
         echo "<pre>" ;
         var_dump ( $ Row );
         echo "</ pre>" ; 
    } 
} 
// Step Six: Close result set
 
mysql_free_result ($ RES); 



// step Seven: release the connection
 
mysql_close ($ conn);

 

() mysql_query function parameters if a query operation, after the implementation of the results of the query returns a pointer to the resource file

　　If the query fails, it returns an empty string

 

Mysql_fetch_ the beginning of the function, a total of four, are able to obtain the results of the function:

mysql_fetch_row : return query results in the form of an indexed array

mysql_fetch_assoc : Returns the associative array

mysql_fetch_array : indexed arrays and associative arrays will return

mysql_fectch_object : Returns the object form

To the above code as an example

Mysql_fetch_assoc output results are as follows:

The results output is changed to mysql_fetch_row

 

dml operations

 Query need to obtain a query result, deletions need not change their operation, so slightly different steps:

? < PHP
 header ( "Content-of the type: text / HTML; charset: UTF-8" );
 // The first step: connect to the database 
$ conn = @ mysql_connect ( 'localhost', 'root', 'root' );
 IF (! $ Conn ) {
     Die ( "connection failed, an error message." mysql_error ()); 
} 
// step: select database 
the mysql_select_db ( "Test" ); 

// third step: character set 
mysql_set_charset ( "utf8 " ); 

// step Four: create sql statement 
$ sql =" `sname` the Delete from the WHERE class = '谢尔顿李库伯'" ; 

// step five:Execute SQL 
$ Exec = mysql_query( $ SQL );
 IF ( the mysql_affected_rows ( $ Conn )) {
     echo 'operation is successful, the recording impact' ; 
} the else {
     echo 'operation failed'. Mysql_error (); 
} 

// do not need to release resources 
// sixth step : release the connection 
mysql_close ( $ conn );

 

And query operations differences:

　　1. determine whether the successful implementation should use mysql_affected_rows () function, rather than mysql_query () function:

 　　　　dml operations are data tables will impact,

　　　　mysql_query () in sql statement even if successfully implemented, it may not have an impact on the data table (such as deleting a nonexistent column, or modify the original results and the results of the same)

　　　　Therefore to determine whether the operation is successful, it is necessary to determine whether the database had an impact, mysql_affected_rows () can achieve this functionality, database changes, the function will return ture, otherwise false

　　2. do not need to shut down the result set, because there is no result set itself

　　3.mysql_query () return value query operations are different from when dml perform, he will return a Boolean value, successful execution is true, failed to false

 

Modify and delete and insert operations is substantially the same operation, only you need to modify corresponding to sql statement.

 

Other database operations

In addition to operating in the data table records, mysql database extensions can perform many operations: as show \ drop \ alter, etc.

To delete the data sheet operations as an example: Compared with dml operation, only need to modify the sql statement and determine whether the statements can be executed successfully

? < PHP
 header ( "Content-of the type: text / HTML; charset: UTF-8" );
 // The first step: connect to the database 
$ conn = @ mysql_connect ( 'localhost', 'root', 'root' );
 IF (! $ Conn ) {
     Die ( "connection failed, an error message." mysql_error ()); 
} 
// step: select database 
the mysql_select_db ( "Test" ); 

// third step: character set 
mysql_set_charset ( "utf8 " ); 

// step Four: create sql statement 
$ sql =" deletetest drop the Table " ; 

// step five:Execute SQL 
IF ( mysql_query ( $ SQL)) {
     Echo 'successful operation' ; 
} the else {
     echo 'operation failed'. Mysql_error (); 
} 

// do not need to release resources 
@ Step Six: releasable connection 
mysql_close ( $ Conn );