Oracle Schedular Job 设置Repeat Interval

   设置Repeat Interval  
　　Job 和Schedule中REPEAT_INTERVAL参数都是用来控制执行的频率或周期，虽然说周期是一个时间性概念，不过REPEAT_INTERVAL指定的时候并不是一个时间值，而是由一组关键字描述的时间。  
 
　　除了前面介绍Job和Schedule的REPEAT_INTERVAL参数时，提到该参数拥有FREQ以及INTERVAL两个关键字，其实除此之外，还有如BYMONTH、BYWEEKNO、BYYEARDAY、BYDATE等等参数，可以用来进行更精确的定义，比如通过BYMONTH关键字指定调度运行的月份，BYDAY指定调度在哪天运行等等。  
 
　　REPEAT_INTERVAL 参数的详细语法如下：  
 
   repeat_interval = regular_schedule | combined_schedule  
  
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regular_schedule = frequency_clause  
 
[";" interval_clause] [";" bymonth_clause] [";" byweekno_clause]  
 
[";" byyearday_clause] [";" bydate_clause] [";" bymonthday_clause]  
 
[";" byday_clause] [";" byhour_clause] [";" byminute_clause]  
 
[";" bysecond_clause] [";" bysetpos_clause] [";" include_clause]  
 
[";" exclude_clause] [";" intersect_clause][";" periods_clause]  
 
[";" byperiod_clause]  
 
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combined_schedule = schedule_list [";" include_clause]  
 
[";" exclude_clause] [";" intersect_clause]  
 
frequency_clause = "FREQ" "=" ( predefined_frequency | user_defined_frequency )  
 
predefined_frequency = "YEARLY" | "MONTHLY" | "WEEKLY" | "DAILY" |   
 
   "HOURLY" | "MINUTELY" | "SECONDLY" 
 
user_defined_frequency = named_schedule  
 
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interval_clause = "INTERVAL" "=" intervalnum  
 
   intervalnum = 1 through 99  
 
bymonth_clause = "BYMONTH" "=" monthlist  
 
   monthlist = monthday ( "," monthday)*  
 
   month = numeric_month | char_month  
 
   numeric_month = 1 | 2 | 3 ...  12  
 
   char_month = "JAN" | "FEB" | "MAR" | "APR" | "MAY" | "JUN" |  
 
   "JUL" | "AUG" | "SEP" | "OCT" | "NOV" | "DEC" 
 
byweekno_clause = "BYWEEKNO" "=" weeknumber_list  
 
   weeknumber_list = weeknumber ( "," weeknumber)*  
 
   weeknumber = [minus] weekno  
 
   weekno = 1 through 53  
 
byyearday_clause = "BYYEARDAY" "=" yearday_list  
 
   yearday_list = yearday ( "," yearday)*  
 
   yearday = [minus] yeardaynum  
 
   yeardaynum = 1 through 366  
 
bydate_clause = "BYDATE" "=" date_list  
 
   date_list = date ( "," date)*  
 
   date = [YYYY]MMDD [ offset | span ]  
 
bymonthday_clause = "BYMONTHDAY" "=" monthday_list  
 
   monthday_list = monthday ( "," monthday)*  
 
   monthday = [minus] monthdaynum  
 
   monthdaynum = 1 through 31  
 
byday_clause = "BYDAY" "=" byday_list  
 
   byday_list = byday ( "," byday)*  
 
   byday = [weekdaynum] day  
 
   weekdaynum = [minus] daynum  
 
   daynum = 1 through 53 /* if frequency is yearly */ 
 
   daynum = 1 through 5  /* if frequency is monthly */ 
 
   day = "MON" | "TUE" | "WED" | "THU" | "FRI" | "SAT" | "SUN" 
 
byhour_clause = "BYHOUR" "=" hour_list  
 
   hour_list = hour ( "," hour)*  
 
   hour = 0 through 23  
 
byminute_clause = "BYMINUTE" "=" minute_list  
 
   minute_list = minute ( "," minute)*  
 
   minute = 0 through 59  
 
bysecond_clause = "BYSECOND" "=" second_list  
 
   second_list = second ( "," second)*  
 
   second = 0 through 59  
 
bysetpos_clause = "BYSETPOS" "=" setpos_list  
 
   setpos_list = setpos ("," setpos)*  
 
   setpos = [minus] setpos_num  
 
   setpos_num = 1 through 9999  
 
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include_clause = "INCLUDE" "=" schedule_list  
 
exclude_clause = "EXCLUDE" "=" schedule_list  
 
intersect_clause = "INTERSECT" "=" schedule_list  
 
schedule_list = schedule_clause ("," schedule_clause)*  
 
schedule_clause = named_schedule [ offset ]  
 
named_schedule = [schema "."] schedule  
 
periods_clause = "PERIODS" "=" periodnum  
 
byperiod_clause = "BYPERIOD" "=" period_list  
 
period_list = periodnum ("," periodnum)*  
 
periodnum = 1 through 100  
 
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offset = ("+" | "-") ["OFFSET:"] duration_val  
 
span = ("+" | "-" | "^") "SPAN:" duration_val  
 
duration_val = dur-weeks | dur_days  
 
dur_weeks = numofweeks "W" 
 
dur_days = numofdays "D" 
 
numofweeks = 1 through 53  
 
numofdays = 1 through 376  
 
minus = "-"   
　　这个语法形式看起来复杂无比，其实实用起来很简单，之所以看起来复杂，是因为其功能太过灵活(之前的三思系列笔记中，已经阐述过灵活与复杂的关系)，这里不准备逐条解释每一个语法细节，下面将着重通过一些常用设置，希望能够更有助于广大同仁的理解。  
 
　　例如：设置任务仅在周5的时候运行：  
 
REPEAT_INTERVAL => 'FREQ=DAILY; BYDAY=FRI';  
 
REPEAT_INTERVAL => 'FREQ=WEEKLY; BYDAY=FRI';  
 
REPEAT_INTERVAL => 'FREQ=YEARLY; BYDAY=FRI';   
　　上述三条语句虽然指定的关键字小有差异，不过功能相同。  
 
　　设置任务隔一周运行一次，并且仅在周5运行：  
 
REPEAT_INTERVAL => 'FREQ=WEEKLY; INTERVAL=2; BYDAY=FRI';   
　　设置任务在当月最后一天运行：  
 
REPEAT_INTERVAL => 'FREQ=MONTHLY; BYMONTHDAY=-1';   
　　设置任务在3月10日运行：  
 
REPEAT_INTERVAL => 'FREQ=YEARLY; BYMONTH=MAR; BYMONTHDAY=10'; REPEAT_INTERVAL => 'FREQ=YEARLY; BYDATE=0310';   
　　上述两条语句功能相同。  
 
　　设置任务每10隔天运行：  
 
REPEAT_INTERVAL => 'FREQ=DAILY; INTERVAL=10';   
　　设置任务在每天的下午4、5、6点时运行：  
 
REPEAT_INTERVAL => 'FREQ=DAILY; BYHOUR=16,17,18';   
　　设置任务在每月29日运行：  
 
REPEAT_INTERVAL => 'FREQ=MONTHLY; BYMONTHDAY=29';   
　　设置任务在每年的最后一个周5运行：  
 
REPEAT_INTERVAL => 'FREQ=YEARLY; BYDAY=-1FRI';   
　　设置任务每隔50个小时运行：  
 
REPEAT_INTERVAL => 'FREQ=HOURLY; INTERVAL=50';   
　　另外，你是否在怀念常规job中设置interval的简便，虽然功能较弱，但是设置操作非常简单，无须懊恼，其实SCHEDULER中的REPEAT_INTERVAL也完全可以按照那种方式设置，前面都说了，REPEAT_INTERVAL实际上是指定周期，直接指定一个时间值，当然也是周期喽。  
 
　　比如说，设置任务每天执行一次，也可以设置REPEAT_INTERVAL参数值如下：  
 
REPEAT_INTERVAL => 'trunc(sysdate)+1'   
　　又比如设置任务每周执行一次：  
 
REPEAT_INTERVAL => 'trunc(sysdate)+7'   
　　不过需要注意，这种方式仅用于创建SCHEDULER中jobs时使用，不能用于schedule。