How to Do Type Casting in SQL Server

By default, SQL Server is not strict with type casting. For example, adding a numeric value in string quotes to another numeric value with not give the usual errors other databases and programming languages will give:

select 10 + '10';

However, should the need arise, you can use either the cast() or the convert() function to force the type of a value.

-- cast float to integer
select cast(1.0123456789 as int);
select convert(int,1.0123456789);

-- cast string to date
select cast('11-02-2020' as date);
select convert(date,'11-02-2020');

-- cast string to decimal
select cast('12.345' as decimal(5,2));
select convert(decimal(15,2),'12.345');

-- cast string to time
select cast('12:45' as time);
select convert(time,'12:45');

You can cast to many SQL Server types such as binary, char, varchar, date, datetime, time, decimal, bigint, and float.