I'm a C# developer trying to become more familiar with SQL Server stored procedures.
I'm a little confused as to why the syntax in "A" works and "B" does not work with Set @id. What is happening here that makes "B" require Select instead of Set?
Example A (works)
DECLARE @currDateTime DateTime
SET @currDateTime = GetDate()
SELECT @currDateTime
Example B (does not work)
DECLARE @id int
SET @id = ID FROM [MyTable] WHERE [Field1] = 'Test'
Example C (works)
DECLARE @id int
SELECT @id = ID
FROM [MyTable]
WHERE [Field1] = 'Test'
SELECT is a built-in type of SQL clause that runs a query and returns a result-set in the format of a table or it assigns variables to the results from a query.
SET is a clause that sets a variable.
The two are very different. SELECT has various other associated clauses, such as FROM, WHERE and so on; SET does not. SELECT returns values as a result table in its normal usage; SET does not.
Admittedly, both look the same in an expression such as:
set @currDateTime = GetDate();
select @currDateTime = GetDate();
However, it is really a coincidence that the syntax for setting a single value happens to look the same.
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