SQL Find Age using DateDiff - sql

Question

Fields || Data
ID || V465
DOB || 1946-09-05
DATE_OF_DEATH || 1974-05-11
I am using this SQL but I am getting an error.
select DATEDIFF("YYYY",'DOB','DATE_OF_DEATH') where ID= 'V465'
Its SQL SERVER Management Studio R2 and
Error: Msg 207, Level 16, State 1, Line 2
Invalid column name 'ID'

Answer 1

You forgot the FROM (and surrounded your column names with single quotes which treats them as string literals):
select DATEDIFF("YYYY",DOB,DATE_OF_DEATH)
FROM {tablename}
where ID= 'V465'
And DATEDIFF alone is not the right way to determine "age" since
DATEDIFF("yyyy",'2001-12-01','2003-01-31')
will give you 2 instead of 1.
See one method here and another here

Answer 2

that error most likely comes from not including a table in your select statement
select DATEDIFF(YY,DOB,DATE_OF_DEATH) AS AGE
FROM TABLE_NAME
where ID= 'V465'

Answer 3

SELECT DATEDIFF(YY,'01-01-2001','12-31-2002')
Returns 1 on MSSQL

Answer 4

Test Data
DECLARE #TABLE TABLE(ID VARCHAR(20),DOB DATE, DATE_OF_DEATH DATE)
INSERT INTO #TABLE VALUES
('V465', '1946-09-05', '1974-05-11'),('V466', '1945-09-05', '2000-11-11'),
('V467', '1982-09-05', NULL),('V468', '1946-09-05', NULL)
Query
SELECT DATEDIFF(YEAR,DOB, COALESCE(DATE_OF_DEATH, GETDATE())) AS AGE
FROM #TABLE
Using COALESCE function if someone hasnt died yet you can calculate their age too. COALESCE function will take difference from date of death and if the column is null it will take difference from today's date. and will give you the following result.
Result
╔═════╗
║ AGE ║
╠═════╣
║ 28 ║
║ 55 ║
║ 32 ║
║ 68 ║
╚═════╝