UPDATE 命令通过更改值来修改现有字段.它使用SET子句指定要修改的列,并指定分配的新值.这些值可以是表达式,也可以是字段的默认值.设置默认值需要使用DEFAULT关键字.该命令还可以使用WHERE子句来指定更新的条件和/或ORDER BY子句以特定顺序更新.
查看以下一般语法 :
UPDATE table_name SET field=new_value, field2=new_value2,... [WHERE ...]
从命令提示符或使用PHP脚本执行UPDATE命令.
At命令提示符,只需使用标准的commandroot :
root@host# mysql -u root -p password; Enter password:******* mysql> use PRODUCTS; Database changed mysql> UPDATE products_tbl SET nomenclature = 'Fiber Blaster 300Z' WHERE ID_number = 112; mysql> SELECT * from products_tbl WHERE ID_number='112'; +-------------+---------------------+----------------------+ | ID_number | Nomenclature | product_manufacturer | +-------------+---------------------+----------------------+ | 112 | Fiber Blaster 300Z | XYZ Corp | +-------------+---------------------+----------------------+
使用 mysql_query()函数在UPDATE命令语句中 :
<?php $dbhost = ‘localhost:3036’; $dbuser = ‘root’; $dbpass = ‘rootpassword’; $conn = mysql_connect($dbhost, $dbuser, $dbpass); if(! $conn ) { die(‘Could not connect: ‘ . mysql_error()); } $sql = ‘UPDATE products_tbl SET product_name = "Fiber Blaster 300z" WHERE product_id = 112’; mysql_select_db(‘PRODUCTS’); $retval = mysql_query( $sql, $conn ); if(! $retval ) { die(‘Could not update data: ‘ . mysql_error()); } echo "Updated data successfully\n"; mysql_close($conn); ?>
成功更新数据后,您将看到以下输出 :
mysql> Updated data successfully