WGU C170 data management – applications Learning checks Exam Questions with complete Answers 2024/2025
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Course
WGU 170
Institution
WGU 170
WGU C170 data management – applications Learning checks Exam Questions with complete Answers 2024/2025
Tables structural rules - no duplicate column names - correct answer duplicate column names are not allowed in one table. However, the same column name can appear in different tables.
Tabl...
WGU C170 data management – applications
Learning checks Exam Questions with
complete Answers 2024/2025
Tables structural rules - no duplicate column names - correct answer duplicate column
names are not allowed in one table. However, the same column name can appear in
different tables.
Tables structural rules - no duplicate rows - correct answer no two rows may have
identical values in all columns.
Data independence - relational databases - correct answer rows and columns of a
table have no inherent order.
Primary keys rules - values must be unique within the column - correct answer this rule
ensures that each value identifies at most one row.
Primary keys rules - values may not be null - correct answer this rule ensures that
each value identifies at least one row.
Composite primary keys rules - column values, when grouped together, must be unique
- correct answer ex: the combination (2538, 1) is unique within (id, number)
Composite primary keys rules - columns may - correct answer not contain null
Composite primary keys rules - composite primary keys - correct answer must be
minimal
A foreign key - correct answer is a column, or group of columns, that refer to a primary
key
Data types of foreign and primary key must be the same.
, Foreign keys rules - foreign key values may be repeated - correct answer ex: sales
and marketing have the same manager.
Foreign keys rules - foreign key values may be null - correct answer ex: technical
support currently has no manager.
Foreign keys rules - non-null foreign key values - correct answer must match some
primary key value.
Referential integrity - correct answer requires that all foreign key values must either be
fully null or match some primary key value.
Referential integrity can be violated in four ways: - correct answer 1. A primary key is
updated.
2. A foreign key is updated.
3. A row containing a primary key is deleted.
4. A row containing a foreign key is inserted.
Databases can automatically correct referential integrity violations with any of four
actions, which are specified in SQL when creating a table with a foreign key: - correct
answer 1. Restrict rejects an insert, update, or delete that violates referential integrity.
2. Set null sets invalid foreign keys to null.
3. Set default sets invalid foreign keys to a default primary key value, specified in SQL.
4. Cascade propagates primary key changes to foreign keys.
Redundancy - correct answer is the repetition of related values
Redundant tables have multiple copies of the same data - correct answer
inconsistency results when updates are not applied uniformly to all copies.
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