我想创建4个表，有外键对方。
表students：

CREATE TABLE students
(
  PRIMARY KEY (student_id),
  student_id SERIAL,
  student_name VARCHAR(100),
  student_age  INT,
  entry_year INT,
  graduate_year INT,
  faculty_name VARCHAR(100),
  group_id INT,
  FOREIGN KEY (group_id) REFERENCES groups(group_id)
);

表groups：

CREATE TABLE groups
  (
PRIMARY KEY (group_id),
group_id   SERIAL,
group_name VARCHAR(100),
  student_id INT,
FOREIGN KEY (student_id) REFERENCES students(student_id)
  );

表lessons：

CREATE TABLE lessons
(
  PRIMARY KEY (lesson_id),
  lesson_id  SERIAL,
  lesson_name  VARCHAR(100),
  class_number INT,
  date TIMESTAMP,
  teacher_id INT,
  group_id INT,
  FOREIGN KEY(teacher_id) REFERENCES teachers(teacher_id),
  FOREIGN KEY (group_id) REFERENCES groups(group_id)
   );

表teachers：

CREATE TABLE teachers
(
  PRIMARY KEY (teacher_id),
  teacher_id INT,
  teacher_name VARCHAR(100),
  position VARCHAR(100)
);

当我在Java应用程序中运行此查询时，我获得了一个创建表students的错误：

nested exception is org.postgresql.util.PSQLException: ERROR: relation "groups" does not exist

我知道为什么会抛出异常，因为我正在从表groups创建带外键的表students，而表groups尚未创建。
但我不知道如何解决它。感谢提前回应！