PHP实现三表联查，实现根据id查询数据 ，并向数据库中添加数据的功能
PHP实现三表联查，实现输入用户id查询出用户姓名、用户角色，输入角色id查询所有用户的ID、姓名和角色，最后实现向数据库中添加用户的功能。
前台页面
表结构
user表
role表
user_role表
代码
data.html
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>用户查询</title>
</head>
<body>
<form method="post" action="selectUser.php" name="search">
查询用户ID：<input name="searchUserId" type="text" value="" size="15"/>
<input type="submit" value="Search" />
</form>
<br>
<br>
<form method="post" action="selectRole.php">
查询角色ID：<input name="searchRoleId" type="text" value="" size="15"/>
<input type="submit" value="Search">
</form>
<br/>
<hr/>
添加用户
<div>
<form action="user_add.php" method="post">
用户ID：   <input type="text" name="user_id" /><br/>
用户姓名：<input type="text" name="user_name" /><br/>
<br/>
<input type="submit" value="添加" />
</form>
</div>
</body>
</html>
selectUser.php
<?php
header("Content-Type:text/html;charset=utf-8");
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test";
//创建连接
$conn = new mysqli($servername,$username,$password,$dbname);
//检测连接
if ($conn->connect_error){
die("连接失败") . $conn->connect_error;
}else{
//var_dump($conn);
//die("数据库连接成功!!!");
// var_dump(111);
}
$searchUserId = $_POST['searchUserId']; //传递search框过来的值
$searchUserId = trim($searchUserId);
if (!$searchUserId && !$searchRoleId)
{
echo '搜索框不能为空.';
exit;
}
$sql = "SELECT u.user_name,r.role_name FROM user as u inner join user_role as ur on u.user_id=ur.user_id inner join role as r on r.role_id=ur.role_id WHERE u.user_id = $searchUserId";
$result = $conn->query($sql);
// echo $sql;
// echo "<br>";
if($result->num_rows > 0){
//输出数据
while ($row = $result->fetch_assoc()) {
echo "用户姓名:" . $row["user_name"] . " " . " 用户角色:" . $row["role_name"];
echo "<br>";
}
}else{
echo "没有该用户！";
}
$conn->close();
selectRole.php
<?php
header("Content-Type:text/html;charset=utf-8");
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test";
//创建连接
$conn = new mysqli($servername,$username,$password,$dbname);
//检测连接
if ($conn->connect_error){
die("连接失败") . $conn->connect_error;
}else{
//var_dump($conn);
//die("数据库连接成功!!!");
// var_dump(111);
}
$searchRoleId = $_POST['searchRoleId']; //传递search框过来的值
$searchRoleId = trim($searchRoleId);
$sql2 = "SELECT ur.user_id,u.user_name,r.role_name FROM role as r inner join user_role as ur on r.role_id=ur.role_id inner join user as u on u.user_id=ur.user_id WHERE r.role_id = $searchRoleId";
$res = $conn->query($sql2);
if ($res->num_rows > 0) {
while($row = $res->fetch_assoc()){
echo "用户ID：" . $row['user_id'] . " " . "用户姓名：" . $row['user_name'] . " " . " 用户角色: " . $row['role_name'];
echo "<br>";
}
}else{
echo "没有该角色！";
}
user_add.php
<?php
header("Content-Type:text/html;charset=utf-8");
$servername = "localhost";
$username = "root";
$password = "";
$db_name = "test";
//创建连接
$conn = new mysqli($servername,$username,$password,$db_name);
//检测连接
if ($conn->connect_error) {
die("连接失败......");
}else{
echo "连接成功!";
}
$user_id = $_POST['user_id'];
$user_name = $_POST['user_name'];
$sql = "INSERT into user(user_id,user_name)Values('$user_id','$user_name')";
if ($conn->query($sql) === TRUE) {
echo "新纪录插入成功！";
}else{
echo "Error" . $sql . "<br>" . $conn->error;
}
$conn->close();
