DECLARE @variable_name INT;
SET @variable_name = 10;
DELETE FROM tblIDNames WHERE nameID < @variable_name;
GO -- << GO is the default batch separator for SSMS query windows and sqlcmd.exe scripts
UPDATE tblIDValues SET IDNumber=0 
WHERE nameID < @variable_name; -- this would generate an error because @variable_name does not exist in this scope, it was declared in a previous batch
GO

TRUNCATE TABLE tblIDNames

DELETE FROM tblIDNames

USE tempdb;
GO
CREATE TABLE a (id INT NOT NULL PRIMARY KEY);
GO
CREATE TABLE b (id INT NOT NULL REFERENCES a(id));
GO
TRUNCATE TABLE a;
GO