我正在通过pgadmin4运行此代码：

CREATE TABLE product(
    code integer, 
    pname varchar(30),
    descr varchar(50),
    utype varchar(30),
    uprice float, 
    manu varchar(30),
    sid integer,
    PRIMARY KEY (code, sid),
    FOREIGN KEY (sid) REFERENCES supplier(sid)
);

CREATE TABLE branch(
    bid integer,
    bname varchar(30),
    baddress varchar(50),
    PRIMARY KEY (bid)
);

CREATE TABLE stock(
    code integer,
    bid integer,
    units float,
    PRIMARY KEY (code, bid)
);

CREATE TABLE receipt(
    bid integer,
    rdate date,
    rtime time,
    ptype varchar(30),
    total float,
    PRIMARY KEY (bid, rdate, rtime)
);

CREATE TABLE purchase(
    bid integer,
    rdate date,
    rtime time,
    code integer,
    units float,
    PRIMARY KEY (bid, rdate, rtime, code),
    check (units > 0)
);

CREATE TABLE supplier(
    sid integer,
    sname varchar(30),
    address varchar(50),
    phone numeric (9,0),
    PRIMARY KEY (sid)
);

INSERT INTO product (code, pname, descr, utype, uprice, manu, sid) VALUES
        (987, 'Tomatoes',       'Vegetable',  'Kg',  5.99,  'manufacturer1', 111),
        (876, 'Cucumbers',      'Vegetable',  'Kg',  4.99,  'manufacturer1', 222),
        (765, 'Cornflakes',     'Cornflakes', 'Box', 15.9,  'manufacturer1', 222),

INSERT INTO branch (bid, bname, baddress) VALUES
        (987, 'tal aviv', 'road 1 tel aviv'),
        (878, 'Raanana',  'road 1 raanana'),
        (767, 'Holon',    'road 1 holon');

INSERT INTO stock (code, bid, units) VALUES
        (987, 989, 50),
        (987, 878, 75),
        (987, 767, 100),

INSERT INTO receipt (bid, rdate, rtime, ptype) VALUES
        (989, '2020-3-19', '10:00', 'Cash'),
        (989, '2020-7-16', '12:30', 'Credit'),
        (989, '2020-7-15', '15:35', 'Credit'),

INSERT INTO purchase (bid, rdate, rtime, code, units) VALUES
        (989, '2020-3-18', '10:00', 987, 5),
        (989, '2020-3-18', '10:00', 876, 3),
        (989, '2020-3-18', '10:00', 543, 4),

INSERT INTO supplier (sid, sname, address, phone) VALUES
        (111, 'supplier2', 'road2 tel aviv',  111111111),
        (222, 'supplier3', 'road3 jerusalem', 222222222),
        (333, 'supplier4', 'road2 eilat',     333333333);

我一直收到这样的消息：错误：关系“供应商”不存在sql状态：42p01
问题是product表（第一个表）中的外键，我知道这一点，因为我删除了它，它创建了所有带有值的表（我删除了一些值以便于编写）。
不确定是否是语法错误，我尝试了几种方法来解决它，但我不知道，有什么建议吗？提前谢谢。