Question

我正在使用来自MySQL数据库的Highcharts创建图表，其中一个图表是一周内新列表的数量。我有一个名为ListDate的日期字段，它有一个索引。

想知道我是否可以（以及如果可以的话如何做）以及我是否应该在ListDate的周上添加一个索引。

这是我的代码，如果它有帮助：

    $Week = 1;
while($Week <= 53)
    {
    $NumListings = $wpdb->get_var("SELECT COUNT(MLSNumber)
    FROM IRES WHERE 
    City = \"$City\" AND
    WEEK(ListDate,3) = $Week AND
    YEAR(ListDate) = $ThisYear AND
    Category=1 AND
    TotalUnits < 2");

    if($NumListings != "" AND $NumListings > 0 AND !(date("Y") == $ThisYear AND date("W") == $Week))
        {
        $Content .= "               [".$Week.", ".$NumListings."],\n";
        }

    $Week++;
    }

Answer 1

直到最近，才在MySQL上执行此操作，在最近发布的MySQL 5.7系列中添加了对虚拟列和索引的支持。

使用细节：http://mysqlserverteam.com/virtual-columns-and-effective-functional-indexes-in-innodb/

Answer 2

我只是运行一个查询来收集数据，而不是执行52个查询。

SELECT WEEK(ListDate,3) AS week, COUNT(MLSNumber) as new_listings
FROM   IRES
WHERE  City = \"$City\"
AND    ListDate between
       -- The 1st of the year through the last day of the year.
       str_to_date(concat('01-01-', '$ThisYear'),'%m-%d-%Y') and
       str_to_date(concat('12-31-', '$ThisYear'),'%m-%d-%Y')
       -- If $ThisYear is the current year, limit to the most recent full week.
AND    ListDate <= curdate() - interval weekday(curdate()) day
AND    Category = 1
AND    TotalUnits < 2
GROUP BY WEEK(ListDate,3);

您可以尝试使用不同的索引来查看效果最好的内容，例如

index(City)
index(City,Category)
index(City,ListDate,Category)
index(ListDate)
index(ListDate,Category)
index(ListDate,City,Category)

在MySQL中添加日期的索引

2 个答案: