Question

我无法将两个MySQL语句合并为一个，目前我必须分别运行它们，然后将它们放入一个数组然后合并这些数组。

这里是函数

第一个功能

/* returns all books from table book */
function getProfitableBooksNew(){
    $q = "SELECT *, 

    ROUND((amazon_new_price/100*80) - lowest_new_price,2) AS margin 

    FROM ".TBL_BOOKS." 

    WHERE rank < 200000 AND rank IS NOT NULL 
    AND lowest_new_price < amazon_new_price/100*80 
    AND amazon_new_price < 9999 
    AND ROUND((amazon_new_price/100*80) - lowest_new_price) > (lowest_new_price/100*".MARGIN.") 

    ORDER BY rank ASC";

    $result = mysql_query($q, $this->connection);

    if(!$result || (mysql_numrows($result) < 1))
        return null;

    $arr = array();
    $numRows = mysql_num_rows($result);//count
    if($numRows>0){
        for($i=0; $i<$numRows; $i++){
            $arr[] = array(
                "isbn"                  => mysql_result($result, $i, "isbn"),
                "title"                 => mysql_result($result, $i, "title"),
                "rank"                  => mysql_result($result, $i, "rank"),                   
                "amazon_price"          => mysql_result($result, $i, "amazon_new_price"),
                "amazon_condition"      => "New",

                "lowest_price"          => mysql_result($result, $i, "lowest_new_price"),
                "lowest_condition"      => "New",

                "margin"                => mysql_result($result, $i, "margin"),

                "last_price_updated"    => mysql_result($result, $i, "last_price_updated"),
                "last_rank_updated"     => mysql_result($result, $i, "last_rank_updated")
            );
        }
    }       

    return $arr;
}

第二个功能

/* returns all books from table book */
function getProfitableBooksUsed(){
    $q = "SELECT *, 

    ROUND((amazon_used_price/100*80) - lowest_used_price, 2) AS margin 

    FROM ".TBL_BOOKS." 

    WHERE rank < 200000 AND rank IS NOT NULL 
    AND lowest_used_price < amazon_used_price/100*80 
    AND amazon_used_price < 9999 
    AND amazon_used_price < amazon_new_price 
    AND ROUND((amazon_used_price/100*80) - lowest_used_price) > (lowest_used_price/100*".MARGIN.") 

    ORDER BY rank ASC";

    $result = mysql_query($q, $this->connection);

    if(!$result || (mysql_numrows($result) < 1))
        return null;

    $arr = array();
    $numRows = mysql_num_rows($result);//count
    if($numRows>0){
        for($i=0; $i<$numRows; $i++){
            $arr[] = array(
                "isbn"                  => mysql_result($result, $i, "isbn"),
                "title"                 => mysql_result($result, $i, "title"),
                "rank"                  => mysql_result($result, $i, "rank"),                   
                "amazon_price"          => mysql_result($result, $i, "amazon_used_price"),
                "amazon_condition"      => mysql_result($result, $i, "amazon_used_condition"),

                "lowest_price"          => mysql_result($result, $i, "lowest_used_price"),
                "lowest_condition"      => "Used",

                "margin"                => mysql_result($result, $i, "margin"),

                "last_price_updated"    => mysql_result($result, $i, "last_price_updated"),
                "last_rank_updated"     => mysql_result($result, $i, "last_rank_updated")
            );
        }
    }       

    return $arr;
}

加入功能

/* returns profitable books */
function getProfitableBooks(){
    $new = $this->getProfitableBooksNew();
    $used = $this->getProfitableBooksUsed();

    if($new && $used){
        return array_merge($new, $used);

    }else if($new){
        return $new;

    }else if($used){
        return $used;

    }else{
        return null;
    }
}

任何人都可以告诉我至少如何解决这个问题？感谢

Answer 1

你可以将这两个查询联合到一个像这样的

的查询中

SELECT *, 

    ROUND((amazon_new_price/100*80) - lowest_new_price,2) AS margin,
    'new' AS type 

    FROM ".TBL_BOOKS." 

    WHERE rank < 200000 AND rank IS NOT NULL 
    AND lowest_new_price < amazon_new_price/100*80 
    AND amazon_new_price < 9999 
    AND ROUND((amazon_new_price/100*80) - lowest_new_price) > (lowest_new_price/100*".MARGIN.") 

UNION

SELECT *, 

    ROUND((amazon_used_price/100*80) - lowest_used_price, 2) AS margin,
    'used' as type 

    FROM ".TBL_BOOKS." 

    WHERE rank < 200000 AND rank IS NOT NULL 
    AND lowest_used_price < amazon_used_price/100*80 
    AND amazon_used_price < 9999 
    AND amazon_used_price < amazon_new_price 
    AND ROUND((amazon_used_price/100*80) - lowest_used_price) > (lowest_used_price/100*".MARGIN.") 

ORDER BY type ASC, rank ASC

注意我添加了一个字段'type'，以便您区分新结果和使用结果。

Answer 2

您可以使用UNION语法

$sql = "(SELECT a FROM t1 WHERE a=10 AND B=1) 
UNION 
(SELECT a FROM t2 WHERE a=11 AND B=2) ORDER BY a LIMIT 10;

如何将两个相似的MySQL语句合并为一个

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