Question
Consider the following database. Employee has a unique eid, name, age and salary. Department has a unique did, name and an employee as a manager.
Consider the following database. Employee has a unique eid, name, age and salary. Department has a unique did, name and an employee as a manager. A department may or may not have a manager assigned. An employee can work for multiple departments. The pct_time in Works table is the percentage of time an employee works for a department. The salary of the employees is fixed and is not based on pct_time or the deparments they work in.
Emp (eid: INT(11), ename: VARCHAR(50), age: INT(11), salary: FLOAT)
Works (eid: INT(11), did: INT(11), pct_time: INT(11))
Dept (did: INT(11), dname: VARCHAR(50, managerid: INT(11))
Constraints
-eid is primary key for Emp table and cannot be NULL
-did is primary key for Dept table and cannot be NULL
-eid and did are foreign keys referencing to Emp and Dept tables respectively in Works table. combination of eid and did is the primary key or works table.
-managerid is foreign key referencing to Emp table and can have NULL values if the department doesnt have a manager assigned.
Sample values.
Emp
eid | ename | age | salary |
1001 | Georgi Facello | 34 | 45000.00 |
1002 | Parto Bamford | 28 | 34000.00 |
1003 | Christian Koblick | 42 | 55000.00 |
1004 | Saniya Peac | 24 | 28000.00 |
Dept
did | dname | managerid |
d001 | Marketing | 1003 |
d002 | Finance | 1002 |
d003 | Information Security | NULL |
Works
eid | did | pct_time |
1001 | d001 | 60 |
1002 | d002 | 100 |
1003 | d001 | 100 |
1001 | d003 | 40 |
1004 | d003 | 50 |
1004 | d002 | 50 |
1. Write the insert statements to enter the above sample values to the database. Add 4 more employees, 2 more departments and assign the 4 new employees to departments with percentage time. Submit all insert statements.
2.Alter the table Emp to change the column age to dob with data type DATE and update the values based on their current age (should be approximate). Submit the alter and update table statement.
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