Transforming Data with SAS Functions
Manipulating SAS Date Values with Functions

MDY Function The MDY function creates a SAS date value from numeric values that represent the month, day, and year. For example, suppose the data set Hrd.Temp contains the employee start date in three numeric variables, Month, Day, and Year.

SAS Data Set Hrd.Temp

City	State	Zip	Phone	Month	Day	Year	PayRate	Days	Hours
CARY	NC	27513	6224549	1	12	2000	10	11	88
CARY	NC	27513	6223251	11	17	1999	8	25	200
CHAPEL HILL	NC	27514	9974749	12	30	1999	40	26	208
RALEIGH	NC	27612	6970450	10	10	1999	15	10	80

Having the start date in three variables makes it hard to perform calculations based on length of employment. You can convert these numeric values to useful SAS date values by applying the MDY function.

General form, MDY function: MDY(month,day,year) where month can be a variable that represents the month or a number from 1-12 day can be a variable that represents the day or a number from 1-31 year can be a variable that represents the year or a number with 2 or 4 digits.

In the data set Hrd.Temp, the values for month, day, and year are stored in the numeric variables Month, Day, and Year. You write the following MDY function to create the SAS date values: mdy(month,day,year) Then place this function in an assignment statement to create a new variable to contain the SAS date values. data hrd.newtemp(drop=month day year); set hrd.temp; Date=mdy(month,day,year); run; Here is the new data set that contains the variable Date.

SAS Data Set Hrd.Newtemp

City	State	Zip	Phone	PayRate	Days	Hours	Date
CARY	NC	27513	6224549	10	11	88	14621
CARY	NC	27513	6223251	8	25	200	14565
CHAPEL HILL	NC	27514	9974749	40	26	208	14608
RALEIGH	NC	27612	6970450	15	10	80	14527

Remember, to display SAS date values in a more readable form, you can associate a SAS format with the values. For example, the FORMAT statement below associates the DATE9. format with the variable Date. A portion of the output that is created by this PROC PRINT step appears below. proc print data=hrd.newtemp; format date date9.; run;

City	State	Zip	Phone	Pay Rate	Days	Hours	Date
CARY	NC	27513	6224549	10	11	88	12JAN2000
CARY	NC	27513	6223251	8	25	200	17NOV1999
CHAPEL HILL	NC	27514	9974749	40	26	208	30DEC1999
RALEIGH	NC	27612	6970450	15	10	80	10OCT1999

The MDY function can also add the same SAS date to every observation. This may be useful if you want to compare a fixed beginning date with differing end dates. Just use numbers instead of data set variables when providing values to the MDY function. data hrd.newtemp; set hrd.temp; DateConstant=mdy(6,17,2002); proc print data=hrd.newtemp; format dateconstant date9.; run;

City	State	Zip	Phone	Pay Rate	Days	Hours	Date Constant
CARY	NC	27513	6224549	10	11	88	17JUN2002
CARY	NC	27513	6223251	8	25	200	17JUN2002
CHAPEL HILL	NC	27514	9974749	40	26	208	17JUN2002
RALEIGH	NC	27612	6970450	15	10	80	17JUN2002

Be careful when entering and formatting year values. The MDY function accepts two-digit values for the year, but SAS software interprets two-digit values according to the 100-year span set by the YEARCUTOFF= system option. The default value of YEARCUTOFF= is 1920. For details, see the lesson Reading Date and Time Values. Whenever possible, use four-digit year values in the MDY function: MDY(5,10,20)   = May 10, 1920 MDY(5,10,2020) = May 10, 2020 To have the years display clearly, format SAS dates with the DATE9. format. This forces the year to appear with four digits, as shown above in the Date and DateConstant variables of your Hrd.Newtemp output.