Destoon secondary development common database operations

This article mainly introduces common database operations for destoon secondary development. For more information, see destoon. after the system is initialized, the system automatically connects to the database and stores the database operation objects in $ db. For database operation methods, see The include/db_mysql.class.php function prototype. Examples of common database operations are given below.

1. execute SQL statements

$db->query("INSERT INTO `{$DT_PRE}table` (`xxx`) VALUES ('yyy')");

$db->query("UPDATE `{$DT_PRE}table` SET `xxx`='yyy' WHERE `zzz`=1");

$db->query("DELETE FROM `{$DT_PRE}table` WHERE `zzz`=1");

2. read multiple messages

$A = array();$result = $db->query("SELECT * FROM `{$DT_PRE}table` WHERE `xxx`='yyy' ORDER BY `zzz` DESC LIMIT 0,10");while($r = $db->fetch_array($result)) {  $A[] = $r;}print_r($A);

3. read a single message

$A = $db->get_one("SELECT * FROM `{$DT_PRE}table` WHERE `xxx`='yyy'");print_r($A);

4. total number of computations

$A = $db->get_one("SELECT COUNT(*) AS num FROM `{$DT_PRE}table` WHERE `xxx`='yyy'");echo $A['num'];

The system table prefix can use the variable $ DT_PRE (usually used in statements) or $ db-> pre (usually used in functions ).
If you use database operations in a function, you must first perform global $ db;