Question

$sql = 'SELECT users.NAME, company.name
FROM users
LEFT JOIN (user_company_access, company) ON (users.USER_ID=user_company_access.company_id AND user_company_access.company_id=company.company_id)
WHERE users.USER_ID="1" AND company.company_id=users.USER_ID';
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
  die('Could not get data: ' . mysql_error());
}
while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
{
    echo "USER ID :"+$row[0]+"  <br> ";
}

我得到了：

Notice: Undefined offset: 0 in C:\xampp\htdocs\index.php on line 23
0
Notice: Undefined offset: 0 in C:\xampp\htdocs\index.php on line 23
0Fetched data successfully

有没有办法直接提取数据？我尝试过类似$ row [＆＃39; users.NAME＆＃39;]的内容，但仍然失败了。

Answer 1

MYSQL_ASSOC返回关联数组而不是数字。所以使用

$row['NAME'];

Answer 2

试试这个，

    SELECT u.NAME AS username , c.name AS companyname
    FROM   users AS u LEFT JOIN user_company_access AS uc ON u.USER_ID=uc.company_id 
                      LEFT JOIN company             AS c  ON uc.company_id=c.company_id
    WHERE  users.USER_ID="1" AND c.company_id=u.USER_ID

    $retval = mysql_query( $sql, $conn );
    if(! $retval )
    {
      die('Could not get data: ' . mysql_error());
    }
    while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
    {
        echo "USER ID :".$row[0]."  <br> ";
        //OR
        // echo "USER ID :".$row['username']."  <br> ";
    }

从查询中提取MySQL数据

2 个答案: