sql server variable

SET @X = 1

make sure you declare that variable before you use that

declare @x int
set @x = 1

SET @X = 1

Msg 137, Level 15, State 1, Line 1
Must declare the scalar variable "@X".

declare
set

were successful

but

INSERT INTO information(
SELECT
(SELECT productid from products where productid = x ),
(select accessoryorder from accessorytypes where accessoryid  = x ),
(SELECT orderid from orders where orderid = x )



Msg 156, Level 15, State 1, Line 2
Incorrect syntax near the keyword 'SELECT'.

INSERT INTO information
SELECT
(SELECT productid from products where productid = x ),
(select accessoryorder from accessorytypes where accessoryid  = x ),
(SELECT orderid from orders where orderid = x )

tried both Z and x


INSERT INTO information
SELECT
(SELECT productid from products where productid = Z ),
(select accessoryorder from accessorytypes where accessoryid  = Z ),
(SELECT orderid from orders where orderid = Z )
select * from information

Msg 207, Level 16, State 1, Line 3
Invalid column name 'Z'.
Msg 207, Level 16, State 1, Line 4
Invalid column name 'Z'.
Msg 207, Level 16, State 1, Line 5
Invalid column name 'Z'.

https://www.experts-exchange.com/questions/25021667/Subquery-returned-more-than-1-value.html

works