Simple Data Complex Data Query 2. Relational DBMS 4. Object-Relational DBMS No Query 1. File System 3. Persistent Language

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CREATE TABLE  emp (
  name       VARCHAR(30),
  startdate  DATE,
  salary     FLOAT,
  dept       VARCHAR(20) );

CREATE TABLE  dept (
  dname   VARCHAR(20),
  budget  FLOAT,
  floor   INTEGER );

• Find the names of employees with an employment start date after 1980 and who earn more than $40,000.
  
  

  SELECT name FROM emp WHERE startdate > '1980-12-31' AND salary > 40000;



• Find the names of employees who work on the first floor.
  
  

  SELECT name FROM emp WHERE dept IN ( SELECT dname FROM dept WHERE floor = 1 );



• Find the average salary of employees in the marketing department.
  
  

  SELECT avg( salary ) FROM emp WHERE dept = 'marketing';