1. database
    a collection of related data organized for some purpose. Some people will use the term database for any type of storage inluding paper files. Most people will assume that the database is a computer system managed by a collection of programs called a database management system (dbms).
  2. relational database
    stores data in structures called relations which can be represented by two-dimensional tables. A relation is a mathematical concept- but we can think of it as a table.
  3. Client
    a porgarm that letsu s work with the database, lets us enter SQL statements and see the results, lets us build database objects such as tables, run scripts
  4. DBMS
    a collection of programs that manage the database
  5. physical data independence
    the user nor the developer need to know the physical orer of the data that is present in the database, data can be queried with out knowledge of the exact order of things physically on the hardware. This is the job of the database admnistrator.
  6. data integrity
    if parameters are set for the data, then the dbms should reject data that does not fit those parameters
  7. query optimization
    the dbms should optimize queries to save processing and user time. This is important when dealing with vaster and vaster amounts of data
  8. Database security
    in terms of user access, is handled by authentication and authorization. Authentication means identifying a user-generally via a login and password
  9. business entity
    the people for which we want to keep the data
  10. attributes
    pieces of data that are stored,

    they are stored in columns
  11. entity instance
    in SQL the entity instance is stored in a row, a column in a table has a name and a data type
  12. constraints
    define rules fo the data = limit the data values that can be entered - i.e. varchar(25) will allow strings of 25 characters or less to be stored.
  13. entity set
    collection of all of the rows in the current tables
  14. primary key
    an attribute or collection of attribues that uniquely identifies that entity sintace. No two rows in the same tables can have the same value for the primary key and no row can be missing a primary key value
  15. normalization
    traditional ruels say that each attribute should storage a single value, all attributes in a row should be determined by the primary key of that entity instance
  16. relationships
    when we store data in tables, we need to organize it efficiently - split the data into several tables and the build relationships between the tables
    can be placed after SELECT to specify that any duplicate copies of an output row will not be displayed.
  18. LIMIT
    a limit clause can be placed at the and of the statement to specify only a specific number of rows that should be displayed if the result is sorted, the sort is done before the limit is applied.
Card Set
Attempt at flashcards for SQL