Lecture 2.1

Structured Query Language

  • data definition language
  • Data manipulation language
  • Industrial standard
Creating a new database structure (schema)
create, alter, drop
Adding information, changing it, or deleting it
insert, update, delete
Finding and extracting subsets of the information in the database

Extracting columns and/or rows/records from a tableProduces a new 'table' based upon an existing set of tables

select <fields> from <table>

<fields> - seperated by comma. * wildcard for everything

Duplicates are not selected (set theory)

Row extraction in SQL

select * from <table> where <field>='<data>' (AND...)

Structural information is carried across to output.