Yout Sql command is Incorrect ,
Insert
Command doesn't have
Where
clause.
Where
Clause is applicable to
Update
,
Select
and
Delete
Commands
insert into tablename (code) values ('1448523')
WHERE not exists(select * from tablename where code='1448523')
you have two ways:
1.
If Not Exists(select * from tablename where code='1448523')
Begin
insert into tablename (code) values ('1448523')
End
2.
insert into tablename (code)
Select '1448523' Where not exists(select * from tablename where code='1448523')