EMPLOYEE Table Column Name Data Type Length EMPID Number 7 EMPNAME Varchar2 25 D
ID: 3851319 • Letter: E
Question
EMPLOYEE Table
Column Name
Data Type
Length
EMPID
Number
7
EMPNAME
Varchar2
25
DEPTID
Number
7
DEPARTMENT Table
Column Name
Data Type
Length
DEPTID
Number
7
DEPTNAME
Varchar2
25
After both tables are created,
1. Add a PRIMARY KEY constraint to the EMPLOYEE table using the EMPID column.
2. Add a PRIMARY KEY constraint to the DEPARTMENT table using the DEPTID column.
3. Add a FOREIGN KEY reference on the EMPLOYEE table so that if a department is deleted from the DEPARTMENT table, any employees in the EMPLOYEE table will automatically be deleted also.
Number 3 is where I am running into trouble, everything I have tried and even solutions that I have found on here have not helped.
Column Name
Data Type
Length
EMPID
Number
7
EMPNAME
Varchar2
25
DEPTID
Number
7
Explanation / Answer
1. Add a PRIMARY KEY constraint to the EMPLOYEE table using the EMPID column.
Answer:
create table employee (empid number(7), empname varchar2(25), deptid number(7));
ALTER TABLE employee ADD CONSTRAINT pk_employee PRIMARY KEY (empid);
2. Add a PRIMARY KEY constraint to the DEPARTMENT table using the DEPTID column.
Answer:
create table department(deptid number(7), deptname varchar2(25));
ALTER TABLE department ADD CONSTRAINT pk_department PRIMARY KEY (deptid);
3. Add a FOREIGN KEY reference on the EMPLOYEE table so that if a department is deleted from the DEPARTMENT table, any employees in the EMPLOYEE table will automatically be deleted also.
Answer:
ALTER TABLE employee ADD CONSTRAINT FK_employee FOREIGN KEY (deptid) REFERENCES department(deptid) ON DELETE CASCADE;
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