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8 Cards in this Set
- Front
- Back
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Classes of DB users |
Main: Database Administrator (DBA) Application Developer End User Other: Security officer Network Administrator Application Administrator |
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DBAs |
People who have central control over the system
Roles include: * Creating the original database schema (by executing a set of DDL statements) * Defining integrity constraints * Allocating system storage * Modifying the schema and physical organisation (to reflect changing needs of org, or to improve performance) * Granting authorisation for data access * Performing routine maintenance (e.g., backing up database, upgrading disk space, monitoring user access and system performance) |
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Application developers |
Design and implement database applications Roles include: * Designing and developing database applications * Estimating storage requirements for the application * Specifying modifications to the DB structure for the application * Relaying this information to the DBA |
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End users |
Interact with the system Roles include: * Entering, modifying and deleting data (where permitted) * Generating reports from the data |
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End user types (I) |
Spectrum from naive to sophisticated
Naive: * use applications that attempt to make operations as simple as possible, using simple commands and menus * don't need to know anything about DB itself (e.g. checkout clerk using barcode scanner to find out price; bank teller posting withdrawals and deposits, DVD store clerk checking out a DVD)
Sophisticated: * Use database query language or data analysis software (or may even write application programs for their own use) |
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End user types (II) |
Casual users: * Can use database query language * Occasionally access database * May need different information each time, so it is not economical to try to write an application to suit their needs
Standalone users: * Maintain personal databases using ready-made software packages that provide easy-to-use interfaces (e.g. tax package, fitness app) |
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Normal forms |
1: no cells with more than one value; Each row identified with unique PK 2: no column functionally dependent on part of PK 3: no column functionally dependent on something that's not part of PK 4: remove multivalued dependencies (e.g. Pizza type, delivery area) |
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Why normalization |
Eliminate redundancy Promote consistency Minimise use of NULLs Prevent loss of information |
