MySQL与MySQLi
导引
从PHP5.5之后，会出现
Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in D:\WEB\wwwroot\test.php on line 23
提示mysql_connect()未来将要被移出。
官网的changelong：
| Version | Function | Description |
|---|---|---|
| 5.5.0 | mysql_connect | This function will generate an E_DEPRECATED error. |
| mysql_db_name | The mysql_list_dbs function is deprecated, and emits an E_DEPRECATED level error. | |
| mysql_pconnect | This function will generate an E_DEPRECATED error. | |
| mysql_tablename | The mysql_tablename function is deprecated, and emits an E_DEPRECATED level error. | |
| 5.3.0 | mysql_db_query | This function now throws an E_DEPRECATED notice. |
| mysql_escape_string | This function now throws an E_DEPRECATED notice. | |
| 4.3.7 | mysql_list_tables | This function became deprecated. |
| 4.3.0 | mysql_escape_string | This function became deprecated, do not use this function. Instead, use mysql_real_escape_string. |
导入数据
导入MySQL示例数据库 employees。
D:\progFiles\mariadb55\employees_db>mysql < employees.sql -u DBAdmin -p Enter password: ******* INFO CREATING DATABASE STRUCTURE INFO storage engine: InnoDB INFO LOADING departments INFO LOADING employees INFO LOADING dept_emp INFO LOADING dept_manager INFO LOADING titles INFO LOADING salaries D:\progFiles\mariadb55\employees_db>
查询数据
查询固定员工ID的姓名，所属部门，职务
以下为创建SQL的过程。
1. 查询姓名
SELECT concat(first_name, ' ' , last_name) as name FROM `employees` WHERE emp_no = 10001
2. 查询部门ID
SELECT dept_no FROM `dept_emp` WHERE emp_no = 10001
3. 查询所在部门名称
SELECT dept_name FROM `departments` WHERE dept_no = (SELECT dept_no FROM `dept_emp` WHERE emp_no = 10001)
4. 查询员工姓名以及部门名称
SELECT concat(e.first_name, ' ' , e.last_name) as name, d.dept_name FROM `employees` e, `departments` d WHERE d.dept_no = (SELECT dept_no FROM `dept_emp` WHERE emp_no = 10001) and e.emp_no = 10001
5. 整合SQL
SELECT
concat(e.first_name, ' ' , e.last_name) as name,
d.dept_name,
t.title
FROM
`employees` e,
`departments` d,
`titles` t
WHERE d.dept_no =
(SELECT dept_no FROM `dept_emp` WHERE emp_no = 10001)
and
e.emp_no = 10001
and
t.emp_no = 10001
mysql
1. 连接
mysql_connect
(
server // 服务器地址
username // 用户名
password // 密码
)
function conn() {
//$con = mysql_pconnect("localhost","root","qazxsw");
$conn = mysql_connect("localhost", "DBAdmin", "xbfirst");
//$conn = mysql_connect("localhost","root","xbfirst80");
//$conn = mysqli=_connect("localhost","tdtc2014","qazxsw");
if (!$conn)
die('Could not connect: ' . mysql_error());
return $conn;
}
2. 查询
(1) 选择数据库
mysql_select_db
(
database_name // 数据库名称
link_identifier // 链接ID
)
(2) 查询语句
mysql_query
(
query // 查询语句
link_identifier // 链接ID
)
(3) 返回结果
mysql_fetch_assoc
(
result // 结果集
)
function myQuery($sql, $conn) {
if (!$conn)
die('Could not connect: ' . mysql_error());
$db_selected = mysql_select_db("carnumber", $conn);
$result = mysql_query($sql,$conn);
while ($row = mysql_fetch_assoc($result)) {
$rows[] = $row;
}
}
mysqli
我们使用Procedural style（过程风格）。
1. 连接
mysqli_connect
(
server // 服务器地址
username // 用户名
password // 密码
)
function conn_i() {
$conn_i = mysqli_connect("localhost", "DBAdmin", "xbfirst");
if (!$conn_i)
die('Could not connect: ' . mysqli_connect_errno());
return $conn_i;
}
2. 查询
(1) 选择数据库
与mysql参数是颠倒的。
mysqli_select_db
(
link_identifier // 链接ID
database_name // 数据库名称
)
(2) 查询语句
与mysql参数是颠倒的。
mysqli_query
(
link_identifier // 链接ID
query // 查询语句
)
(3) 返回结果
mysqli_fetch_assoc
(
result // 结果集
)
function myQuery_i($sql_i, $conn_i) {
if (!$conn_i)
die('Could not connect: ' . mysqli_connect_errno());
$db_selected = mysqli_select_db($conn_i, "carnumber");
$result_i = mysqli_query($conn_i, $sql_i);
while($row_i = mysqli_fetch_assoc($result_i))
{
$rows_i[] = $row_i;
}
}
附：
test.php
<?php
phpinfo();
testQuery();
function testQuery() {
$sql = "SELECT
concat(e.first_name, ' ' , e.last_name) as name,
d.dept_name as dept,
t.title as title
FROM
`employees` e,
`departments` d,
`titles` t
WHERE
d.dept_no =
(SELECT dept_no FROM `dept_emp` WHERE emp_no = 10001)
and
e.emp_no = 10001
and
t.emp_no = 10001";
if (version_compare(PHP_VERSION, '5.5.0') >= 0) {
$conn_i = conn_i();
myQuery_i($sql, $conn_i);
closeConn_i($conn_i);
}
else {
$conn = conn();
myQuery($sql, $conn);
closeConn($conn);
}
}
function conn() {
//$con = mysql_pconnect("localhost","root","qazxsw");
$conn = mysql_connect("localhost", "DBAdmin", "xbfirst");
//$conn = mysql_connect("localhost","root","xbfirst80");
//$conn = mysql_connect("localhost","tdtc2014","qazxsw");
if (!$conn)
die('Could not connect: ' . mysql_error());
return $conn;
}
function closeConn($conn) {
mysql_close($conn);
}
function myQuery($sql, $conn) {
if (!$conn)
die('Could not connect: ' . mysql_error());
$db_selected = mysql_select_db("employees", $conn);
$result = mysql_query($sql,$conn);
while ($row = mysql_fetch_assoc($result)) {
$rows[] = $row;
}
foreach ($rows as $r) {
echo 'name: ' . $r['name'] . '</br>';
echo 'department: ' . $r['dept'] . '</br>';
echo 'title: ' . $r['title'];
}
}
function conn_i() {
$conn_i = mysqli_connect("localhost", "DBAdmin", "xbfirst");
if (!$conn_i)
die('Could not connect: ' . mysqli_connect_errno());
return $conn_i;
}
function closeConn_i($conn_i) {
mysqli_close($conn_i);
}
function myQuery_i($sql_i, $conn_i) {
if (!$conn_i)
die('Could not connect: ' . mysqli_connect_errno());
$db_selected = mysqli_select_db($conn_i, "employees");
$result_i = mysqli_query($conn_i, $sql_i);
while($row_i = mysqli_fetch_assoc($result_i))
{
$rows_i[] = $row_i;
}
foreach($rows_i as $row_i)
{
echo 'name: ' . $row_i['name'] . '</br>';
echo 'department: ' . $row_i['dept'] . '</br>';
echo 'title: ' . $row_i['title'];
}
/* free result set */
mysqli_free_result($result_i);
}
?>
运行效果：
参考文章:
《MySQL vs. MySQLi: Is the Improvement Right for You?》
《MySQL vs MySQLi in PHP》
《MySQL 官方示例数据库安装》