Question

我需要一个查询，它会从datetime中存储的日期减去1个月，以便我可以在谷歌折线图中使用它。我现在的查询是

$sql_query = "SELECT count(ip_address) AS count, 
                    DATE(visit_date_time) as visit_date_time 
            FROM db_views 
            WHERE user_id = $id 
            GROUP BY DATE(visit_date_time) 
            ORDER BY visit_date_time LIMIT 30 ";

减去1个月就像“0月1日”，“1月2月”.....，“11月12日”。

我使用过dateadd＆amp; datesub但没有得到理想的结果并最终出错。

更新

这是完整的代码。

$sql_query = "SELECT count(ip_address) AS count, DATE(visit_date_time) as visit_date_time, MONTH(DATE(visit_date_time)) - 1 mon FROM db_views WHERE user_id = '".$_SESSION[$mainfunctions->GetLoginSessionVar()]."' GROUP BY DATE(visit_date_time) ORDER BY visit_date_time LIMIT 30 ";
$result = mysqli_query($mainfunctions->connection,$sql_query);

echo "{ \"cols\": [ {\"id\":\"\",\"label\":\"Date\",\"pattern\":\"\",\"type\":\"date\"}, {\"id\":\"\",\"label\":\"Views\",\"pattern\":\"\",\"type\":\"number\"} ], \"rows\": [ ";
$total_rows = mysqli_num_rows($result);
$row_num = 0;
while($row = mysqli_fetch_array($result)){
    $row_num++;
    $vDate = str_replace("-", ",",$row['visit_date_time']);
    if ($row_num == $total_rows){
      echo "{\"c\":[{\"v\":\"Date(".$vDate.")\",\"f\":null},{\"v\":" . $row['count'] . ",\"f\":null}]}";
    } else {
      echo "{\"c\":[{\"v\":\"Date(".$vDate.")\",\"f\":null},{\"v\":" . $row['count'] . ",\"f\":null}]}, ";
    }
}
echo " ] }";
mysqli_close($mainfunctions->connection);

我的输出：{"v":"Date(2017,01,02)","f":null},{"v":6,"f":null}

所需输出：{"v":"Date(2017,00,02)","f":null},{"v":6,"f":null}

Answer 1

您可以在查询中使用它：

SELECT DATE_FORMAT('2017-01-21 12:36:32','%m') -1;

结果：0

<强>样品

得到以0开头的月份数。month_number 1和2得到相同的结果

$sql_query = "SELECT count(ip_address) AS count, 
               DATE(visit_date_time) as visit_date_time,
               MONTH(visit_date_time) as month_number_1,
               DATE_FORMAT(visit_date_time,'%m') -1 as month_number_2
            FROM db_views 
            WHERE user_id = $id 
            GROUP BY DATE(visit_date_time) 
            ORDER BY visit_date_time LIMIT 30 ";

Answer 2

使用MONTH函数从日期时间中提取月份（在您的情况下可能为visit_date_time）并从中减去1。

SELECT 
    COUNT(ip_address) AS count,
    DATE(visit_date_time) AS visit_date_time,
    MONTH(DATE(visit_date_time)) - 1 mon
FROM
    db_views
WHERE
    user_id = $id
GROUP BY DATE(visit_date_time)
ORDER BY visit_date_time
LIMIT 30

Answer 3

在mysql中没有找到任何正确的解决方案。所以我使用PHP代码来获得所需的输出。这是用于减去1个月的代码

$vDate = str_replace("-","",$row['visit_date_time'])-100;
$vDate = substr_replace($vDate,",",6,0);
$vDate = substr_replace($vDate,",",4,0);

如果mysql中有任何解决方案。请告诉我。

从数据库的datetime列减去1个月

3 个答案: