Question

我一直在尝试制作一个程序，它将从我的数据库读取所有列，如果这些列具有相同的年龄，则会出现多次（例如，如果两行具有相同的年龄15，则应显示这两行）

这是我试图制作的代码：

include('dbcon_3.php');  

if ( $mysqli->connect_errno ) {
    printf("Connect failed: %s\n", $mysqli->connect_error);
    exit();
}

$sql = "SELECT * FROM table2 GROUP BY Age HAVING ( COUNT( Age ) > 1 )";
$result = $mysqli->query( $sql );
if ( $result->num_rows > 0 ) {
  while ( $row = $result->fetch_row() ) {
     for ( $j = 0; $j <= count( $row ) - 1; $j++ ) {
        echo  $row[$j];
     }
  }
} else if ( $result->num_rows == 0 ) {
   echo "Not found";
}

此代码的结果只是应该出现的行之一（我已经测试了三行，一个是16岁，两个是15岁。从最后两个只有一个出现在屏幕上）。

提前致谢。

Answer 1

GROUP BY崩溃你的命中。你可以解决这个问题：

SELECT * FROM table2 WHERE Age IN 
(SELECT Age from table2 GROUP BY Age HAVING (COUNT(Age) > 1))

Answer 2

您也可以使用子查询

SELECT table2.* FROM table2 
JOIN
(SELECT age FROM table2 GROUP BY Age HAVING (COUNT(Age) > 1)) AS temp 
ON temp.age=table2.age

Answer 3

SELECT Surname  
FROM table2 
GROUP BY Name 
group by Age 
HAVING (COUNT(Age) > 1)

没有显示所有结果

3 个答案: