Database Modification

Deletion

• DELETE from <table> - deletes everything in the table
• DELETE FROM <table> WHERE <condition> - deletes rows conditionally from the table

Insertion

• INSERT into <table> values (tuple) - inserts a row into the table
• null may be inserted in any cell as well
• INSERT into <table>(tuple) values (tuple) - inserts into some rows only
• you can also insert the result of one query into another table

Update

• UPDATE <table> SET <attribute> = <value>
• UPDATE instructor SET salary = 1.05 * salary is a valid query

Case

• case is used to implement an if else

  UPDATE instructor
      SET salary = CASE
          WHEN salary <= 100000 THEN salary * 1.05
                                ELSE salary * 1.03
          END