db2 - 计算两个日期之间的天数，不包括周末

Question

如何在 DB2 中找到两个日期之间的差异（不包括周末）？

DB2 中是否有任何函数可以做到这一点？还是我需要自己写一个查询？

Answer 1

AFAIK 没有这样的功能。然而，编写一个计算这个的查询很容易：

with cal(d) as ( 
    values date('2015-01-01') -- start_date 
    union all 
    select d + 1 day from cal 
    where d < '2015-01-15'    -- end_date 
) select count(case when dayofweek(d) between 2 and 6 then 1 end) 
  from cal;

如果您进行大量此类计算，您可能想要创建一个日历表，您可以将国庆节等属性添加到该表中。

Answer 2

you can use this function:

DAYOFWEEK(CURRENT_DATE)

The following calculation will return the number of working days between two dates:

[Week(End Date) - Week(Start Date)] * 5 + [DayofWeek(Start Date) - DayofWeek(End Date)]

This will only work if the functions for Week and Day or equivalent are native to the database driver. Client Access and Sybase native connection both support these functions.

The Week function will give the integer value of the week of the year selected. The DayofWeek will give an Integer value from 1-7 for the day selected.

IBM Support Working Days Between Two Dates

Answer 3

这是实现两个日期之间差异的最佳方式，不包括周末意味着周六和周日，也不包括国定假日....

  /******
   * First, we'll extend the date object with some functionality.
   *   We'll add an  .each() function, as well as an .adjust() function.
   *   .each()  will give us the ability to loop between two dates, whether
   *     by 'day', 'week' or 'month'.
   *   .adjust() will allow us to move a given day by a given unit. This is used
   *     like so: currentDate.adjust('days', 1) to increment by one day.
   ******/
  Date.prototype.each = function(endDate, part, step, fn, bind){
  	var fromDate = new Date(this.getTime()),
  		toDate = new Date(endDate.getTime()),
  		pm = fromDate <= toDate? 1:-1,
  		i = 0;

  	while( (pm === 1 && fromDate <= toDate) || (pm === -1 && fromDate >= toDate) ){
  		if(fn.call(bind, fromDate, i, this) === false) break;
  		i += step;
  		fromDate.adjust(part, step*pm);
  	}
  	return this;
  };
  
  Date.prototype.adjust = function(part, amount){
	part = part.toLowerCase();
	
	var map = { 
				years: 'FullYear', months: 'Month', weeks: 'Hours', days: 'Hours', hours: 'Hours', 
				minutes: 'Minutes', seconds: 'Seconds', milliseconds: 'Milliseconds',
				utcyears: 'UTCFullYear', utcmonths: 'UTCMonth', weeks: 'UTCHours', utcdays: 'UTCHours', 
				utchours: 'UTCHours', utcminutes: 'UTCMinutes', utcseconds: 'UTCSeconds', utcmilliseconds: 'UTCMilliseconds'
			},
		mapPart = map[part];

	if(part == 'weeks' || part == 'utcweeks')
		amount *= 168;
	if(part == 'days' || part == 'utcdays')
		amount *= 24;
	
	this['set'+ mapPart]( this['get'+ mapPart]() + amount );

	return this;
}
  
  
/*******
 * An array of national holidays. This is used to test for the exclusion of given
 *   days. While this list is national days, you could tailor it to regional, state
 *   or given religious observances. Whatever.
 ******/
natDays = [
  {
    month: 1,
    date: 26,
    type: "national - us",
    name: "New Year's Day"
  },
  {
    month: 1,
    date: 21,
    type: "national - us",
    name: "Martin Luther King Day"
  },
  {
    month: 2,
    date: 18,
    type: "national - us",
    name: "President's Day (Washington's Birthday"
  },
  {
    month: 5,
    date: 27,
    type: "national - us",
    name: "Memorial Day"
  },
  {
    month: 7,
    date: 4,
    type: "national - us",
    name: "Independence Day"
  },
  {
    month: 9,
    date: 2,
    type: "national - us",
    name: "Labor Day"
  },
  
  {
    month: 10,
    date: 14,
    type: "national - us",
    name: "Columbus Day"
  },
  {
    month: 11,
    date: 11,
    type: "national - us",
    name: "Veteran's Day"
  },
  {
    month: 11,
    date: 29,
    type: "national - us",
    name: "Thanksgiving Day"
  },
  {
    month: 12,
    date: 25,
    type: "national - us",
    name: "Christmas Day"
  }
  
];

/******
 * This uses the national holidays array we just set, and checks a given day to see
 *   if it's in the list. If so, it returns true and the name of the holiday, if not
 *   it returns false.
 *****/
function nationalDay(date) {
    for (i = 0; i < natDays.length; i++) {
      if (date.getMonth() == (natDays[i].month-1)
          && date.getDate() == natDays[i].date) {
        return [true, natDays[i].name];
      }
    }
  return [false, null];
}

/******
 * This function takes two dates, as start and end date, and iterates through the
 *   dates between them. For each date, it checks if the current date is a week day.
 *   If it is, it then checks if it isn't a holiday. In this case, it increments
 *   the business day counter.
 ******/
function calcBusinessDays(startDate, endDate) {
  // input given as Date objects
  var iDateDiff=0, holidays = [];
    
  startDate.each(endDate, 'days', 1, function(currentDate, currentStep, thisDate){
      if(currentDate.getDay() != 0 && currentDate.getDay() != 6 ) {
        var isAHoliday = nationalDay(currentDate);
          if(!isAHoliday[0]){
            iDateDiff += 1;
          } else {
            holidays.push(isAHoliday[1]);
          }
      }
   });
   return {count: iDateDiff, holidays: holidays};

};

$(function(){
  var results, exclusions;

$( "#startDate" ).datepicker({
      defaultDate: "+1w",
      changeMonth: true,
      numberOfMonths: 3,
      onClose: function( selectedDate ) {
        $( "#endDate" ).datepicker( "option", "minDate", selectedDate );
      }
    });
    $( "#endDate" ).datepicker({
      defaultDate: "+1w",
      changeMonth: true,
      numberOfMonths: 3,
      onClose: function( selectedDate ) {
        $( "#startDate" ).datepicker( "option", "maxDate", selectedDate );
      }
    });
    $("#calculateMe").on("click", function(){
      var startDate = new Date($("#startDate").val()),
          endDate = new Date($("#endDate").val() );
      // Calculate the number of business days. This returns an object, with
      //  two members: count and holidays
      results = calcBusinessDays(startDate, endDate);
      exclusions = "Excluded weekends";
      if (results.holidays.length > 0) {
        // We have holidays, tell the user about them...
        exclusions += " and the following holidays: ";
        for(var i=0; i<results.holidays.length; i += 1){
          exclusions += results.holidays[i]+", ";
        }
      } else {
        // No holidays.
        exclusions += ".";
      }
      $("#result").text(results.count + " business days." ).append("<p>("+exclusions+")</p>");
    });
});

<div id="content">
    <input type="text" class="myDateClass" id="startDate"/>    
    <input type="text" class="myDateClass" id="endDate"/>
    <button id="calculateMe">How many business days?</button>
    <div id="result"></div>
</div>

小提琴