Translating ER Diagrams with Key Constraints

• Map relationship to a table:

  • Note that did is the key now!
  • Separate tables for Employees and Departments.

• Since each department has a unique manager, we could instead combine Manages and Departments.

CREATE TABLE Manages(

ssn CHAR(11),

did INTEGER,

since DATE,

PRIMARY KEY (did),

FOREIGN KEY (ssn) REFERENCES Employees,

FOREIGN KEY (did) REFERENCES Departments)

CREATE TABLE Dept_Mgr(

did INTEGER,

dname CHAR(20),

budget REAL,

ssn CHAR(11),

since DATE,

PRIMARY KEY (did),

FOREIGN KEY (ssn) REFERENCES Employees)

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