Question

<?php

$query1 = "CREATE VIEW current_rankings AS SELECT * FROM main_table WHERE date = X";

$query2 = "CREATE VIEW previous_rankings AS SELECT rank FROM main_table WHERE date = date_sub( X , INTERVAL 1 MONTH)";

$query3 = "CREATE VIEW final_output AS SELECT current_rankings.player, current_rankings.rank as current_rank LEFT JOIN previous_rankings.rank as prev_rank
             ON (current_rankings.player = previous_rankings.player)";

$query4 = "SELECT *, @rank_change = prev_rank - current_rank as rank_change from final_output";

$result = mysql_query($query4) or die(mysql_error()); 

while($row = mysql_fetch_array($result)) {
echo $row[ player ]. $row[ current_rank ]. $row[ prev_rank ]. $row[ rank_change ];
}

?>

All the queries work independently but am really struggling putting all the pieces together in one single result so I can use it with mysql_fetch_array.

我试图提出看法和临时表格,但每次都说桌上不存在,或回到空洞的阵列圈......当时有这样的情况,但我认为,由于这是我第一次必须处理多个问题,我需要将所有问题合并在一起。期待得到一些支持。许多感谢。

Answer 1

得益于php。我先提出一个解决办法:你必须使用<代码>(Msqli_multi_query($link,$query)来进行多次压缩的询问。

 /* create sql connection*/
$link = mysqli_connect("server", "user", "password", "database");

$query = "SQL STATEMENTS;"; /*  first query : Notice the 2 semicolons at the end ! */
$query .= "SQL STATEMENTS;"; /* Notice the dot before = and the 2 semicolons at the end ! */
$query .= "SQL STATEMENTS;"; /* Notice the dot before = and the 2 semicolons at the end ! */
$query .= "SQL STATEMENTS"; /* last query : Notice the dot before = at the end ! */

/* Execute queries */

if (mysqli_multi_query($link, $query)) {
do {
    /* store first result set */
    if ($result = mysqli_store_result($link)) {
        while ($row = mysqli_fetch_array($result)) 

/* print your results */    
{
echo $row[ column1 ];
echo $row[ column2 ];
}
mysqli_free_result($result);
}   
} while (mysqli_next_result($link));
}

EDIT——如果你真的想要做一个大的问答,那么上述解决办法就会发挥作用,但正如你所希望的那样,还可以单独执行许多问询。

$query1 = "Create temporary table A select c1 from t1"; 
$result1 = mysqli_query($link, $query1) or die(mysqli_error());

$query2 = "select c1 from A"; 
$result2 = mysqli_query($link, $query2) or die(mysqli_error());

while($row = mysqli_fetch_array($result2)) {

echo $row[ c1 ];
    }

Answer 2

看来,你没有执行定购单1 - que3。如果其他人没有首先被处决,那么你就只能ski到4美元。

Also

$query4 = "SELECT *, @rank_change = prev_rank - current_rank as rank_change from final_output";

可能的话

$query4 = "SELECT *, @rank_change := prev_rank - current_rank as rank_change from final_output";

或者说,如果“变换”等于(前_rank - 现任_rank),那么“变化”的等级价值就只是一个 b子。但是,你们是否完全需要@rank_change? 您是否在随后的询问中使用? 也许你可以完全去除。

更糟的是,你只能把所有问题都归为这样的问题:

SELECT 
    curr.player,
    curr.rank AS current_rank,
    @rank_change := prev.rank - curr.rank AS rank_change
FROM
    main_table AS curr
    LEFT JOIN main_table AS prev
        ON curr.player = prev.player    
WHERE 
    curr.date = X
    AND prev.date = date_sub( X , INTERVAL 1 MONTH)

Answer 3

您应召集他们:

<?php

$query = "CREATE VIEW current_rankings AS SELECT * FROM main_table WHERE date = X";

$query .= " CREATE VIEW previous_rankings AS SELECT rank FROM main_table WHERE date =     date_sub( X , INTERVAL 1 MONTH)";

$query .= " CREATE VIEW final_output AS SELECT current_rankings.player,     current_rankings.rank as current_rank LEFT JOIN previous_rankings.rank as prev_rank
         ON (current_rankings.player = previous_rankings.player)";

$query .= " SELECT *, @rank_change = prev_rank - current_rank as rank_change from final_output";

$result = mysql_query($query) or die(mysql_error()); 

while($row = mysql_fetch_array($result)) {
echo $row[ player ]. $row[ current_rank ]. $row[ prev_rank ]. $row[ rank_change ];
}

?>

友情链接