I'm very new to SQL and just practicing for my SQL exam by going through past papers, however, I'm stuck on how to implement the staffID & projNo in the allocation table to be both primary and foreign keys. I've tried to use solutions online but none work. 

Here is the relational schema (**PK**, *FK*)

```
staff( **staffID**, firstname, lastName, gender, dob, jobTitle)

project ( **projNo**, projName, description )

allocation ( ***staffID***, ***projNo***, hours )

```

Here is my SQL:

```
CREATE TABLE staff (
  staffID CHAR (4) PRIMARY KEY,
  firstName VARCHAR (30) NOT NULL,
  lastName VARCHAR (30) NOT NULL,
  gender CHAR (1) CHECK (gender IN ('M','F'))
  dob DATE NOT NULL,
  jobTitle VARCHAR (30) NOT NULL,
  );

CREATE TABLE project (
  projNo CHAR (4) PRIMARY KEY,
  projName VARCHAR (20) NOT NULL,
  description VARCHAR (30) NOT NULL,
  );

CREATE TABLE allocation (
  staffID CHAR (4) 
  projNo CHAR (4) 
  hours int (2)
  );

```