如何在MySQL

Question

我試圖執行這個查詢從兩個表兩列，但我得到的錯誤「未定義指數： L-NAME」。我想從表和 一列（FNAME）計算行從其他表中選擇列（lname）。所以請幫助我。

$result = mysql_query("SELECT COUNT(fname),lname FROM a,b"); 
    while ($row = mysql_fetch_array($result)) 
    { 
     echo "<tr><td>"; 
     echo $row['lname']; 
     echo "</td>"; 
     echo "<td>"; 
     echo $row['COUNT(fname)']; 
     echo "</td></tr>"; 
    } 

Answer 1

您需要使用的別名。使用此：

$result = mysql_query("SELECT COUNT(fname) AS countfname,lname FROM a,b"); 
while ($row = mysql_fetch_array($result)) 
{ 
    echo "<tr><td>"; 
    echo $row['lname']; 
    echo "</td>"; 
    echo "<td>"; 
    echo $row['countfname']; 
    echo "</td></tr>"; 
} 

Answer 2

試試這個代碼：

$result = mysql_query("SELECT COUNT(a.fname) as fname,b.lname as lname FROM a,b"); 
while ($row = mysql_fetch_array($result)) 
{ 
    echo "<tr><td>"; 
    echo $row['lname']; 
    echo "</td>"; 
    echo "<td>"; 
    echo $row['COUNT(fname)']; 
    echo "</td></tr>"; 
} 

Answer 3

如果仍然出現錯誤，你可以嘗試分別取兩個：

$result = mysql_query("SELECT COUNT(fname) FROM a"); 
while ($row = mysql_fetch_array($result)) 
    { 
    echo "<tr><td>"; 
    echo $row['COUNT(fname)']; 
    echo "</td></tr>"; 

    } 

$result1 = mysql_query("SELECT lname FROM b"); 
while ($row = mysql_fetch_array($result1)) 
    { 
     echo "<tr><td>"; 
     echo $row['lname']; 
     echo "</td></tr>"; 
    }