The DATE function takes a month, day and year number and converts it into a number representing the Microsoft Excel date-time code. An important function to know for use in dashboard construction and use with lookup problems involving date/times where the date is broken apart.
The DATE function is a computer program that you run from a worksheet cell formula. It converts a month, day and year number to a serial number that Excel recognizes as a date. You run the DATE function by typing its name in a formula then followed by the information it is suppose to use. The DATE worksheet function is used with functions like the VLOOKUP, MATCH and similar functions because when they lookup dates they are looking for the serial number not a date format. So in other words, 1/1/2015 will not work as the first argument of VLOOKUP. The DATE worksheet function is also used heavily with dashboard interfaces taking the ActiveX control numbers they output and turning them into dates.
Whenever you type a formula in a worksheet cell, this is called syntax or grammar. The general DATE function syntax has a format like this when you type it in a worksheet cell:
= DATE( year, month, day )
Where year, month... is called the function argument list. Remember, you are running a computer program at this point so the program needs information to operate and that is why there is an argument list. When you see an argument list and you see square brackets [ ] around the argument name, this means the argument is optional and you do not have to include it when typing unless you need it. So for the syntax above, you need to include 3 arguments for the DATE function when typing it in a worksheet cell formula in order for it to calculate correctly. What argument values can be used are discussed below. Remember functions expect certain things in their argument lists, if you do not put the correct information in the list they will generate an error when run.
Since the DATE function is a computer program, it runs when you press Enter to enter the formula that contains it. If any of its arguments are wrong, the function will return an error.
When typing the DATE function in a worksheet cell formula, you need to replace its arguments with the month, day and year numbers needed. Some typical arguments you can use are:
|Argument Type||Cell Formula||Example Explanation|
|Cell Reference||= DATE( A1, A2, A3 )||Returns a serial date number based upon the numbers in cells' A1, A2 and A3. For example if 2015,1,1 where in those cells then 42005 would be returned|
|Range Reference||= DATE( A1:A10, B1:B10, C1:C10 )||Returns an array of serial date numbers based upon the months, days and years in the cell ranges|
The worksheet seen below contains some typical worksheet formulas that run the DATEVALUE and DATE worksheet function. Pay close attention to the argument list and the syntax used to write the formula.
|4||Formula below uses DATEVALUE that splices the date together from table above so VLOOKUP can use it to lookup a serial date number in another table|
|5||= VLOOKUP ( DATEVALUE( A2 & "/" & B2 & "/" & C2), $G$1:$K$100, 3, FALSE )|
|6||You can also use the DATE function for the same effect as DATEVALUE above when dealing with date number parts in seperate columns|
|7||= VLOOKUP ( DATE( C2, A2, B2 ), $G$1:$K$100, 3, FALSE )|
|8||Last day of a month calculation so formula below would return 11/30/2015. Very important trick to know when building interfaces that deal with date ranges|
|=DATE( 2015, 12, 0 )|