Using the SQL table data from this question: https://www.chegg.com/homework-help

Question

Using the SQL table data from this question:
https://www.chegg.com/homework-help/questions-and-answers/create-department-tables-based-following-column-name-id-name-data-type-number-varchar2-len-q30116538

Answe the following.

- Add a foreign key reference on the EMPLOYEE table that will ensure that the employee is not assigned to a nonexistent department.
- Confirm that the constraints were added by querying USER_CONSTRAINTS. Note the types and names of the constraints and include them in your statement comments.
- Display the object names and types from the USER_OBJECTS data dictionary view for EMPLOYEE and DEPARTMENT tables. You will want to format the columns for readability. Provide comments that include the new tables and indexes created.
- Modify the EMPLOYEE table by adding a SALARY column of NUMBER data type, precision 7.

Explanation / Answer

1.ALTER TABLE EMPLOYEE ADD CONSTRAINT add_fk FOREIGN KEY (dept_id) REFERENCES department (id);
2.
SELECT constraint_name, constraint_type FROM USER_CONSTRAINTS WHERE table_name IN('EMPLOYEE', 'DEPARTMENT');
4.
ALTER TABLE EMPLOYEE ADD (SALARY NUMBER (7));

3.
COLUMN object_name FORMAT A30
COLUMN object_name FORMAT A30
SELECT object_name,object_type FROM user_objects WHERE object_name LIKE 'EMPLOYEE%' OR onject_name LIKE 'DEPARTMENT%';

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