Question

我知道从开始日期和结束日期开始，您可以使用connect by选择该范围内的所有日期。但是我很难将其概括为多个开始和结束日期。这是一个简化的例子（使用数字而不是日期）：

select
    name,
    min + level
from (
    select 'foo' as name, 0 as min, 5 as max from dual
    union all
    select 'bar' as name, 10 as min, 20 as max from dual
)
connect by nocycle
    (prior name = name) and level <= (max - min);

我希望得到15行，但我只得到2.简化查询：

select
    name,
    min + level
from (
    select 'foo' as name, 0 as min, 5 as max from dual
)
connect by nocycle
    level <= (max - min);

我按预期得到了五行。但以下只返回一个：

select
    name,
    min + level
from (
    select 'foo' as name, 0 as min, 5 as max from dual
)
connect by nocycle
    (prior name = name) and level <= (max - min);

同样，莫名其妙地，以下内容：

select
    name,
    min + level
from (
    select 'foo' as name, 0 as min, 5 as max from dual
)
connect by nocycle
    (prior name = name or 1=1) and level <= (max - min);

这里发生了什么，我该如何解决？

Answer 1

补救措施：请勿使用$username = "Doe"; $logname = "John"; $query=mysqli_query($db_conx, "SELECT s.id, s.account_name, s.author, s.data, s.postdate FROM status s INNER JOIN friends f ON f.user1='$username' OR f.user2='$username' WHERE s.account_name='$username' OR s.author='$username' OR s.account_name='$logname' OR s.author='$logname' GROUP BY s.id ORDER BY s.postdate DESC"); //I have also tried these two queries but not giving me what I want //$query = mysqli_query($db_conx, "SELECT * FROM status WHERE account_name = '$username' OR author = '$username' ORDER BY postdate DESC"); $num_row = mysqli_num_rows($query); echo " Numbers ".$num_row; //$query =mysqli_query($db_conx, "SELECT s.* , f.* FROM status s, friends f WHERE s.account_name='$user' AND f.user1='$user' OR f.user2='$user'"); while($row=mysqli_fetch_array($query)) { ?> <tr> <td><?php echo $row['data']; ?></td> <td><?php echo $row['id']; ?></td> <td><?php echo $row['author']; ?></td> <td><?php echo $row['account_name']; ?></td> </tr> <?php }。要打破循环，请使用PRIOR添加一个条件，这将强制每行中有一个唯一的附加（系统提供）列。标准为connect by nocycle

说明：而不是重新发明方向盘，https://community.oracle.com/thread/2526535

重写第一个查询：

... and prior sys_guid() is not null

无法使用connect by生成多个值范围

1 个答案: