如何从一个数据库中的多个表中获取多个值？

Question

我有一个严重的问题！

我想使用数据库中不同表的不同值。我的桌子：

用户

user_id |姓名 |电邮 |密码 |颜色 |已创建

parents

parent_id |电邮 |密码

所以，我想将这些表格与电子邮件列联系起来。但是密码列不同。

这是我的代码：

        $_SESSION['logged_in2'] = false;
    if( !empty( $data ) ){

        // Trim all the incoming data:
        $trimmed_data = array_map('trim', $data);

        // escape variables for security
        $email = mysqli_real_escape_string( $this->_con,  $trimmed_data['email'] );
        $password = mysqli_real_escape_string( $this->_con,  $trimmed_data['password'] );

        if((!$email) || (!$password) ) {
            throw new Exception( PARENTS_FIELDS_MISSING );
        }
        $password = md5( $password );

        $query = "SELECT parent_id, email FROM parents where email = '$email' and password = '$password' union all SELECT name FROM users ";
        $result = mysqli_query($this->_con, $query);
        $data = mysqli_fetch_assoc($result);
        $count = mysqli_num_rows($result);
        mysqli_close($this->_con);
        if( $count == 1){
            $_SESSION = $data;
            $_SESSION['logged_in2'] = true;
            return true;
        }else{
            throw new Exception( PARENTS_FAIL );
        }
    } else{
        throw new Exception( PARENTS_FIELDS_MISSING );
    }

如何在一个代码中使用这些表？请帮忙！对了，错误是这样的：

mysqli_fetch_assoc() 期望参数 1 为 mysqli_result，布尔值给定 mysqli_num_rows() 期望参数 1 为 mysqli_result，布尔值给定

Answer 1

也许使用这样的组合查询（连接）：

select a.*, b.* from table users as a join parents as b on a.email = b.email where a.email = "$email" and a.password = "$password"

已更新：

SELECT b.user_id, a.email, b.email as parent_email, a.name, a.color, b.password as parent_password FROM users AS a INNER JOIN parents AS b ON a.email = b.email WHERE b.email = '$email' AND b.password  = '$password' ;

$email = mysqli_real_escape_string( $this->_con, $trimmed_data['parent_email'] );
$password = mysqli_real_escape_string( $this->_con, $trimmed_data['parent_password'] );

如何从一个数据库中的多个表中获取多个值？

How to get multiple values from multiple tables in one db?

php

mysqli

multiple-tables