Question: I have two variables `@date` of type `datetime` and `@time` of type `time`. I want to add both to get another `datetime` variable. And I want to perform further calculations on it.

Ex: 

```
Declare @date datetime
Declare @time time

```

I want something like this

```
@date = @date + @time (but not concatenation)

SELECT @Startdate = DATEADD(DAY, -1, @date )

```

Is there any way?

Answer: 
The only thing you are missing is that @time needs to be cast back to a datetime before adding to @date.

```
declare @date datetime = '2022-05-26'
declare @time time = '09:52:14'
declare @Startdate datetime

set @date = @date + convert(datetime,@time)

SELECT @Startdate = DATEADD(DAY, -1, @date)

```

Produces:
[![enter image description here](https://i.stack.imgur.com/gp3eh.png)](https://i.stack.imgur.com/gp3eh.png)
First of all convert `@date` and `@time` variables to `NVARCHAR()`, then concat them and after It convert It to `DATETIME` datatype. After It you can use `DATEADD` function on It. Try in following:

```
DECLARE @date DATETIME 
DECLARE @time TIME

SET @date = GETDATE()
SET @time = '10:12:13'

SELECT DATEADD(DAY, -1, CAST(CONVERT(NVARCHAR(20), @date, 110) + ' ' +
                             CONVERT(NVARCHAR(20), @time, 108) AS DATETIME))

```

**OUTPUT** (*Today day -1 + time '10:12:13'*):

```
2015-07-16 10:12:13.000

```