SQL Server 2019

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CREATE TABLE Producto
(
    Idproducto int  PRIMARY KEY NOT NULL,
    Nombre varchar(100) NOT NULL,
    Precio_Unitario DECIMAL  (18,2),
    constraint chk1 check (Precio_Unitario <> 0)
);
insert into Producto (Idproducto, Nombre, Precio_Unitario) values (1, 'A', 2);
1 rows affected

insert into Producto (Idproducto, Nombre, Precio_Unitario) values (2, 'B', null);
1 rows affected

insert into Producto (Idproducto, Nombre, Precio_Unitario) values (3, 'C', 0);
Msg 547 Level 16 State 0 Line 1
The INSERT statement conflicted with the CHECK constraint "chk1". The conflict occurred in database "fiddle_914c4e0be5e144138dc870cf3d5a6ced", table "dbo.Producto", column 'Precio_Unitario'.
Msg 3621 Level 0 State 0 Line 1
The statement has been terminated.