Writing Basic SQL SELECT Statements

• Show the structure of the DEPARTMENTS table. Select all data from the table.

DESC departments;

SELECT * 

FROM departments;

• Show the structure of the EMPLOYEES table. Write a query to display the last name, job code, hire date and employee number for each employee, with employee number appearing first. 

DESC employees;

SELECT employee_id, last_name, job_id, hire_date 

FROM employees; 

• Create a query to display unique job codes from the EMPLOYEES table. 

SELECT DISTINCT job_id

FROM employees;

• Write a query to display the column headings Emp #, Employee, Job, and Hire Date, respectively, from the EMPLOYEES table. 

SELECT employee_id "Emp #", last_name "Employee", job_id "Job", hire_date "Hire Date" 

FROM employees;

Note: You can also use AS to display the column with other name. For ex: in above query you can also write: SELECT employee_number AS "Emp #" from emp; 

• Display the last name concatenated with the Job ID, separated by a comma and space, and name the column Employee and Title.

SELECT last_name||', '||job_id "Employee and Title" 

FROM employees;

• Create a query to display all the data from the EMPLOYEES table. Separate each column by a comma. Name the column THE_OUTPUT. 

SELECT employee_id||','||last_name||','||job_id||','||manager_id||','||hire_date||','||salary||','||commission_pct "THE_OUTPUT" 

FROM employees;