年だけならこれでもいい。
IF( NOT( ISBLANK( Birthdate ) ) ,
IF( DATE( 2000 , MONTH( Birthdate ) , DAY( Birthdate ) ) <= DATE( 2000 , MONTH( TODAY() ) , DAY( TODAY() ) ),
YEAR (Today()) - YEAR ( Birthdate ),
YEAR (Today()) - YEAR ( Birthdate ) -1 ),
null)
月と日もいるらしい。
IF(
datetime_1 - datetime_2 > 0 ,
TEXT( FLOOR( datetime_1 - datetime_2 ) ) & " days "
& TEXT( FLOOR( MOD( (datetime_1 - datetime_2 ) * 24, 24 ) ) ) & " hours "
& TEXT( ROUND( MOD( (datetime_1 - datetime_2 ) * 24 * 60, 60 ), 0 ) ) & " minutes",
""
)
IF( NOT( ISBLANK( Birthdate)),
YEAR(DATEVALUE(CreatedDate))-YEAR(Birthdate )-
IF(ADDMONTHS(Birthdate ,12*(YEAR(DATEVALUE(CreatedDate))-YEAR(Birthdate )))<=DATEVALUE(CreatedDate), 0,1), NULL)
IF( NOT( ISBLANK( Birthdate)),
YEAR(TODAY())-YEAR(Birthdate )-
IF(ADDMONTHS(Birthdate ,12*(YEAR(TODAY())-YEAR(Birthdate )))<=TODAY(), 0,1), NULL)