PHP日期处理,mysql按日期、时间查询

date_default_timezone_set('PRC'); //默认时区
echo "今天:",date("Y-m-d",time()),"<br>";
echo "今天:",date("Y-m-d",strtotime("18 june 2008")),"<br>";
echo "昨天:",date("Y-m-d",strtotime("-1 day")), "<br>";
echo "明天:",date("Y-m-d",strtotime("+1 day")), "<br>";
echo "一周后:",date("Y-m-d",strtotime("+1 week")), "<br>";
echo "一周零两天四小时两秒后:",date("Y-m-d G:H:s",strtotime("+1 week 2 days 4 hours 2 seconds")), "<br>";
echo "下个星期四:",date("Y-m-d",strtotime("next Thursday")), "<br>";
echo "上个周一:".date("Y-m-d",strtotime("last Monday"))."<br>";
echo "一个月前:".date("Y-m-d",strtotime("last month"))."<br>";
echo "一个月后:".date("Y-m-d",strtotime("+1 month"))."<br>";
echo "十年后:".date("Y-m-d",strtotime("+10 year"))."<br>";

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#mysql查询今天、昨天、7天、近30天、本月、上一月 数据
#今天
select * from 表名 where to_days(时间字段名) = to_days(now());
#昨天
SELECT * FROM 表名 WHERE TO_DAYS( NOW( ) ) – TO_DAYS( 时间字段名) <= 1
#7天
SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 7 DAY) <= date(时间字段名)
#近30天
SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= date(时间字段名)
#本月
SELECT * FROM 表名 WHERE DATE_FORMAT( 时间字段名, ‘%Y%m’ ) = DATE_FORMAT( CURDATE( ) , ‘%Y%m’ )
#上一月
SELECT * FROM 表名 WHERE PERIOD_DIFF( date_format( now( ) , ‘%Y%m’ ) , date_format( 时间字段名, ‘%Y%m’ ) ) =1