问题
How can I find the difference between two dates in DB2 (excluding weekends)?
Are there any functions that will do this in DB2? Or do I need to write a query myself?
回答1:
There is AFAIK no such function. It is however easy to write a query that calculates this:
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;
If you do a lot of these kind of calculations you might want to create a calendar table, you can add attributes like national holiday etc to this table.
回答2:
This is the best way to implement difference between two dates excluding weekend means Saturday and Sunday and also excluding national holiday....
/******
* 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>Fiddle
来源：https://stackoverflow.com/questions/27731712/count-days-between-two-dates-excluding-weekends