Replace year in datetime date

Question

I have a table with a column (dateDT), formatted as datetime and a variable input for the year (@selYear) in my Select, formatted as int.

How can I replace the year within a date from my table with the variable input and return the result in datetime format (within a Select) ?

I have tried the following but this returns wrong dates / years:

CONVERT(DATETIME, (@selYear + MONTH(dateDT) + DAY(dateDT))) AS dateDT,

Example:

@selYear = 2014
dateDT = 2010-05-02 00:00:00.000

In this case my result should be:

dateDT = 2014-05-02 00:00:00.000

Answer 1

A solution using DATEADD function:

DECLARE @selYear VARCHAR(4) = 2014
DECLARE @dateDT DATETIME = '2010-05-02 00:00:00.000'


SELECT DATEADD(YEAR,@selYear - YEAR(@dateDT),@dateDT)

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This is example with smaller then current year:

DECLARE @selYear INT = 2009
DECLARE @dateDT DATETIME = '2010-05-02 00:00:00.000'


SELECT DATEADD(YEAR,@selYear - YEAR(@dateDT),@dateDT)