Wednesday, 15 April 2015

Updating Records

The update statement is used to update or change records that match a specified criteria. This is accomplished by carefully constructing a where clause.
update "tablename"
set "columnname" = 
    "newvalue"
 [,"nextcolumn" = 
   "newvalue2"...]
where "columnname" 
  OPERATOR "value" 
 [and|or "column" 
  OPERATOR "value"];

 [] = optional
[The above example was line wrapped for better viewing on this Web page.]
Examples:
update phone_book
  set area_code = 623
  where prefix = 979;

update phone_book
  set last_name = 'Smith', prefix=555, suffix=9292
  where last_name = 'Jones';

update employee
  set age = age+1
  where first_name='Mary' and last_name='Williams';

Update statement exercises

After each update, issue a select statement to verify your changes.
  1. Jonie Weber just got married to Bob Williams. She has requested that her last name be updated to Weber-Williams.
  2. Dirk Smith's birthday is today, add 1 to his age.
  3. All secretaries are now called "Administrative Assistant". Update all titles accordingly.
  4. Everyone that's making under 30000 are to receive a 3500 a year raise.
  5. Everyone that's making over 33500 are to receive a 4500 a year raise.
  6. All "Programmer II" titles are now promoted to "Programmer III".
  7. All "Programmer" titles are now promoted to "Programmer II".
Create at least 5 of your own update statements and submit them.

SQL Interpreter

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