PHP MySQL基本語法(連接、查詢SELECT)

1.連接資料庫，確認資料庫是否存在

//MySQL位置
$db_host = "localhost";

//資料庫名稱
$db_database = "database";

//MySQL帳號
$db_username = "account";

//MySQL密碼
$db_password = "password";

//是否可連到MySQL
if (!@mysql_connect($db_host, $db_username, $db_password)) die("Error");

//是否可連上資料庫
if (!@mysql_select_db($db_database)) die("Error");

//連接MySQL Server
$conn=mysql_connect($db_host, $db_username, $db_password);

//連接資料庫
mysql_select_db($db_database,$conn);

//指定編碼
mysql_query("set names 'utf8'");

2.查詢(SELECT)

a.一般查詢

//db_table為資料表名稱，*為指定所有欄位
$sql = mysql_fetch_array(mysql_query("select * from `db_table`"));

b.查詢條件資料

//field為欄位名稱，value為資料值，field1為指定顯示的欄位
$sql = mysql_fetch_array(mysql_query("select `field1` from `db_table` where `field` = 'value'"));

//and 兩個條件都必須成立
$sql = mysql_fetch_array(mysql_query("select `field1` from `db_table` where `field` = 'value' and `field1` = 'value1'"));

//or 其中一個成立
$sql = mysql_fetch_array(mysql_query("select `field1` from `db_table` where `field` = 'value' or `field1` = 'value1'"));

c.查詢後排序

//欄位field由大而小排序
$sql = mysql_fetch_array(mysql_query("select * from `db_table` order by `field` desc"));

//欄位field由小而大排序
$sql = mysql_fetch_array(mysql_query("select * from `db_table` order by `field` asc"));



d.印出所有資料

$sql = mysql_query("select * from `db_table`");
while($sql_rows = mysql_fetch_array($sql)){
    echo $sql_rows["field1"];
    echo $sql_rows["field2"];
    echo $sql_rows["field3"];
    .
    .
    .
}