SQL ORACLE - "Table or view does not exist"

Question

CREATE TABLE Order_Item
(
    Tree_ID VARCHAR(30) PRIMARY KEY
    REFERENCES Tree(ID),
    Order_ID VARCHAR(30) NOT NULL,
    FOREIGN KEY (Order_ID) REFERENCES Order_Form(Order_ID)
);


CREATE TABLE Tree
(
    ID VARCHAR(30) PRIMARY KEY,
    Roottype VARCHAR(30) NOT NULL,
    FOREIGN KEY (Roottype) REFERENCES Rootstock(Rootstocktype),
    Variety VARCHAR(60) NOT NULL,
    FOREIGN KEY (Variety) REFERENCES Variety(Name),
    Age NUMBER(9) NOT NULL,
    CHECK (Age >= 0),
    Pot_Size NUMBER(9) NOT NULL,
    CHECK (Pot_Size >= 0),
    Price NUMBER(9) NOT NULL,
    CHECK (Price >= 0),
    Available_On VARCHAR(100) NOT NULL
);

Can someone explain to me why im getting this error code? Thank You

Answer 1

Oracle checks if all objects you are creating exists. When you try to create table Order_Item, your schema is referencing another table that you are creating later. The solution is create first tables without references and finally most complex tables.