68 Multiple choice questions
- • The database must already meet the requirements of both 1NF and 2NF.
• The database must not contain any columns that aren't fully dependent upon the primary key.
- an attribute or set of attributes that can be used to uniquely identify each row.
- with a non-clustered index
- Transact-SQL script statements
- • Columns containing a unique key constraint may contain only one row with a NULL value.
• A table may have multiple unique constraints.
- "provide a fact about the key, the whole key, and nothing but the key."
- same record in the primary key table.
- secondary table.
- to a primary key (...)
- The data in the rows are sorted in only one order.
- primary key is defined for a table.
»» . Right-click the table and select Design view »» Table Designer »»
Select Relationships »» Select the table to which you wish to add the
foreign key constraint »» Tables and Columns Specification »» Click the
ellipsis (. . .) »» Select the table that your foreign key refers to in
the primary key table »» OK »» Close »» Save All
- functionally dependent upon the entire primary key.
- locking contention and improves multiple-user performance.
- Primary keys, foreign keys, and composite (unique) keys.
- NULL value in the same option, as that would violate the unique constraint's duplicate value error.
- enforce the uniqueness property of columns, in addition to a primary key within a table.
- Isolate independent multiple relationships
- the composite primary key plays an important role.
- alternate keys.
- attribute depends on the key but also on another nonkey attribute.
- All the potential primary keys.
- uniquely identifies each row of data.
- • The table must have no duplicate records.
• The table also must not have multivalued attributes..
• The entries in the column or attribute must be of the same data type.
- increases the speed of data retrieval.
- difficult to modify.
- Eliminate redundant data
»» right-clicking the table and selecting Design »» Table Designer »»
select Indexes/Keys »» Click on the Add button to create a new key »»
the Type property in the right side of the property box and change it
from the default of Index to Unique Key »» Columns property section,
Click (. . .) »» Close »» Save All
- clustered table
- "many-to-many" relationship between the Customer and Products tables.
- corresponding values in the primary key table.
- you define more than one column as your primary key.
- • Tables that define entities
• Tables that relate entities
- an attribute depends on only part of the key.
- foreign key.
- unique and must have a value that is not null.
- the fourth normal form
- the design violates the fourth normal form.
- each attribute does in fact describe the entity.
- transitive dependency
- logical or software-based.
- foreign key in one of the tables to the primary key of the referenced table.
- the elimination of redundant data to save space.
- We can simply compute the TOTAL "on the fly" when performing database queries.
We can now use the following query in order to achieve the same results, without violating normalization rules:
SELECT OrderNumber, UnitPrice * Quantity
»» Databases folder »» Tables folder »» Indexes subfolder »» New index
»» New Index properties box »» This is where you would select whether
the index you are creating is to be clustered or non-clustered.
- Eliminate repeating groups
- primary key; without a primary key, it's not a valid table.
- not fully dependent on the primary key.
- mechanisms that are used to prevent simultaneous changes to the database
- • Development costs
- attribute1 is dependent on attribute2, which is then dependent on the primary key.
process of organizing data in order to reduce redundancy by dividing a
database into two or more tables and then defining table relationships.
- transitive dependencies.
- you have met the first normalized form criterion.
- moving the nondependent attribute to a new entity.
- Isolate semantically related multiple relationships
- Eliminate columns not dependent on key
- overwritten by another transaction that executes at the same time.
- development costs.
- second normal form.
- understand a database and write correct queries.
- SQL Server Management Studio.
the repeating group of tour attributes into a single unique attribute
and then move any multiple values to a unique table.