# How To Calculate Age In A DataStage Transformer

Occasionally, there is a need to calculate the between two dates for several reasons. For example, the age of a person, of an asset, age of an event.  So, having recently had to think about how to do this in a DataStage Transformer rather than in SQL, I thought it might be good to document a few approaches that can provide the age.

## Calculating Age With the DecimalToDecimal function

This code does it at the year level; however, if you need the decimal digits or other handling, the rounding within the DecimalToDecimal function can be changed accordingly.

### Age Calculation using Julian Date

DecimalToDecimal((JulianDayFromDate(<>) – JulianDayFromDate(Lnk_In_Tfm.PROCESSING_DT) )/365.25, ‘trunc_zero’)

### Age Calculation using Julian Date with Null Handling

Null handling is recommended to prevent job failure if a date is missing from your source input data.  This code uses 1901-01-01 as the null replacement value, but it can be any date your business requirement stipulates.

DecimalToDecimal((JulianDayFromDate( NullToValue(<>, StringToDate(‘1901-01-01’,”%yyyy-%mm-%dd”) ) )  – JulianDayFromDate(Lnk_In_Tfm.PROCESSING_DT)) /365.25, ‘trunc_zero’)

### Calculate Age Using DaysSinceFromDate

DecimalToDecimal(DaysSinceFromDate(<>, <>) /365.25 , ‘trunc_zero’)

### Calculate Age Using DaysSinceFromDate with Null Handling

Here is a second example of applying null handling to the input data.

DecimalToDecimal(DaysSinceFromDate(<>, NullToValue(<< Input date (e.g.Date of Birth) >>, StringToDate(‘1901-01-01’,”%yyyy-%mm-%dd”) ) ) /365.25 , ‘trunc_zero’)