String concatenation in procedure parameters - sql

Question

I want to do something like this:
declare #var varchar(50) = '2';
exec sp_myprocedure 'first', 'sec ' + #var
but I get an error:
Incorrect syntax near '+'.
Of course I can set variable before exec procedure:
set #var = 'sec ' + #var;
but I don't want this, because I have many execution in my code and I don't want create million variables.

Answer 1

You need to fix your code, sorry. There is no magic that will make this legal:
EXEC dbo.procedure_name #var + 'constant';
Also, STOP using the sp_ prefix for stored procedures.

Answer 2

I think it's not possible to use string concatenation in procedure execution if you're using EXEC.
From this:
Execute a stored procedure or function
[ { EXEC | EXECUTE } ]
{
[ #return_status = ]
{ module_name [ ;number ] | #module_name_var }
[ [ #parameter = ] { value
| #variable [ OUTPUT ]
| [ DEFAULT ]
}
]
[ ,...n ]
[ WITH <execute_option> [ ,...n ] ]
} [;]
The #parameter must be a value.
But this: 'sec ' + #var is an expression.

Answer 3

You don't need to declare a million variables, you simply need to declare a single variable, and set it prior to each EXEC:
DECLARE #cmd nvarchar(max) = '';
declare #var varchar(50) = '2';
set #cmd = 'sec ' + #var;
exec sp_myprocedure 'first', #cmd
set #cmd = 'try ' + #var;
exec sp_myprocedure 'first', #cmd
set #cmd = 'foo ' + #var;
exec sp_myprocedure 'first', #cmd
set #cmd = 'bar ' + #var;
exec sp_myprocedure 'first', #cmd