php学习笔记

使用Mysqli实现增删改查

1.连接数据库

//连接数据库
//$database: 数据库名
public function connect($database) {
$servername = "localhost";
$username = "root";
$password = "root";
$dbname = $database;

// 创建连接
$this->conn = new mysqli($servername, $username, $password, $dbname);

// 检测连接
if ($this->conn->connect_error) {
die("连接失败: " . $this->conn->connect_error);
}
// echo '连接成功<br />';
// return $this->conn;
}

2.获取一条数据

//获取一条数据
//$table: 数据表
//$where: 要查询的数据， 默认为空
public function getOne($table, $where = '') {
if($where != "") {
$sql = "SELECT * FROM {$table} WHERE {$where}";
}
else {
$sql = "SELECT * FROM {$table}";
}

$result = $this->conn->query($sql);

$data = [];

$row = mysqli_num_rows($result);

if ($row > 0) {
$data = mysqli_fetch_assoc($result);
// echo '查询成功<br />';
return $data;
}
else {
// echo '查询失败<br />';
return false;
}
}

3.获取多条数据

//获取所有数据
//$table: 数据表
//$where: 要查询的数据, 默认为空
public function getAll($table, $where = '') {
if($where != "") {
$sql = "SELECT * FROM {$table} WHERE {$where}";
}
else {
$sql = "SELECT * FROM {$table}";
}

$result = $this->conn->query($sql);

$data = [];

$row = mysqli_num_rows($result);

if ($row > 0) {
while($row = mysqli_fetch_assoc($result)) {
$data[] = $row;
}
// echo '查询成功<br />';
return $data;
}
else {
// echo '查询失败<br />';
return false;
}
}

}

4.插入数据

//插入数据
//$table: 数据表
//$data: 要插入的数据
public function insert($table, $data) {
$fields = "";
$values = "";
//拼接sql,把data解析成字段和值，可以实现复用
foreach ($data as $key => $value) {

if ($fields == "") {
$fields = $key;
}
else {
$fields = $fields.','.$key;
}

if ($values == "") {
$values = "'".$value."'";
}
else {
$values = $values.",'".$value."'";
}

}

//sql语句
$sql = "INSERT INTO {$table} ({$fields})
VALUES ({$values})";

$result = $this->conn->query($sql);
if ($result == true) {
// echo '插入成功<br />';
return true;
}
else {
// echo '插入失败<br />';
return false;
}
}

5.删除数据

//删除数据
//$table: 数据表
//$where: 删除条件
public function delete($table, $where) {
$sql = "DELETE FROM {$table} WHERE {$where}";

$result = $this->conn->query($sql);

$row = mysqli_affected_rows($this->conn);

if ($row > 0) {
//echo '删除成功<br />';
return true;
}
else {
//echo '删除失败<br />';
return false;
}
}

6.更新数据

//更新数据
//$table: 数据表
//$data: 要更新的数据
//$where: 更新条件
public function update($table, $data, $where) {
$before = "UPDATE {$table} SET ";
$after = " WHERE {$where}";

$fields = "";
foreach ($data as $key => $value) {
if ($fields == "") {
$fields = "{$key} = "."'{$value}'";
}
else {
$fields = $fields.",{$key} = "."'{$value}'";
}
}

//sql语句
$sql = $before.$fields.$after;

$result = $this->conn->query($sql);

$row = mysqli_affected_rows($this->conn);

if ($row > 0) {
// echo '修改成功<br />';
return true;
}
else {
// echo '修改失败<br />';
return false;
}
}

第一次发博客，纪念一下。