Database Application
→ Software that helps business users interact with database systems.
Database Administrator
→ Responsible for securing the database system against unauthorized users. A database
administrator enforces procedures for user access and database system availability.
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WGU - D426: Objective Assessment
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Database Application
→ Software that helps business users interact with database systems.
Database Administrator
→ Responsible for securing the database system against unauthorized users. A database
administrator enforces procedures for user access and database system availability.
Authorization
→ Many database users should have limited access to specific tables, columns, or rows of
a database. Database systems authorize individual users to access specific data.
Rules
→ Database systems ensure data is consistent with structural and business rules.
Query Processor
→ Interprets queries, creates a plan to modify the database or retrieve data, and returns
query results to the application. Performs query optimization to ensure the most
efficient instructions are executed on the data.
Storage Manager
→ Translates the query processor instructions into low-level file-system commands that
modify or retrieve data. Database sizes range from megabytes to many terabytes, so
the storage manager uses indexes to quickly locate data.
→ Ensures transactions are properly executed. The transaction manager prevents conflicts
between concurrent transactions. The transaction manager also restores the database
to a consistent state in the event of a transaction or system failure.
Metadata
→ Data about the database, such as column names and the number of rows in each table.
Relational Database
→ Stores data in tables, columns, and rows, similar to a spreadsheet.
Relational Database
→ All _________ ________ systems support the SQL query language.
Relational Database
→ Relational systems are ideal for databases that require an accurate record of every
transaction, such as banking, airline reservation systems, and student records.
MongoDB (NoSQL)
→ The newer non-relational systems are called NoSQL, for 'not only SQL', and are
optimized for big data.
SQL Statements
→ INSERT inserts rows into a table.
→ SELECT retrieves data from a table.
→ UPDATE modifies data in a table.
→ DELETE deletes rows from a table.
→ A statement that creates a new table by specifying the table and column names. Each
column is assigned a data type that indicates the format of column values. Data types
can be numeric, textual, or complex.
Data Type
→ INT stores integer values.
→ DECIMAL stores fractional numeric values.
→ VARCHAR stores textual values.
→ DATE stores year, month, and day.
→ This phase specifies database requirements without regard to a specific database
system. Requirements are represented as entities, relationships, and attributes. An
entity is a person, place, activity, or thing. A relationship is a link between entities, and
an attribute is a descriptive property of an entity.
Logical Design (Database Design)
→ This phase implements database requirements in a specific database system. For
relational database systems, _________ design converts entities, relationships, and
attributes into tables, keys, and columns.
Physical Design
→ Specifies indexes, table structures, and partitions. This phase adds indexes and
specifies how tables are organized on storage media. Affects query processing speed
but never affects the query result.
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