- Shape database is 3 :
- concept
- logical
- physical
The concept :
Entities : Objects in which data is collected it can be a person , place , event , or just the concept of a physical object .
External entities : Entities used for the data exchanged, but that is not stored in the database.
Attribute : A unit facts about specific entities : the fact must be atomic ( divided ) .
Relationship: Association among entities .
Business Rules : Policies, procedures or standards that define the organization uses and specific control over data : often implemented in the database as a constraint.
The maximum cardinality : the maximum number of entities can be associated withminimum : the minimum number of entities can be associated withtransferable : relationship transferable if the parents which may change from time to time00:59
Conditional in one direction : means a record that matches may or may not be found on the contact options
Conditional in both directions : means a record that matches may or may not be available on both sides of the relationship
Mandatory in one direction : means matching records must exist in the mandatory relationship
One to many: to show that the records in a table may be related to many ( usually 0 + ) record in the other table .
room: small units called data in the database
- The type of data helps keep dtabase data efficiently.
restict of data attribute values into the correct data type and provides a set of
- Behavior that is consistent with the type of data set ( such as addition, subtraction , etc.untuknombor ) .Unfortunately , different vendors support different data types zoo .
constraints : rules that restrict the values of the data allowed
* Primary key : one or more columns that uniquely identifies a specific row in the table.
- Constraints are duplicate values are not allowed n the primary key column ( s ) table .
- key is usually performed as an index .
indexes speed up searches.
Foreign key : a field -side side a one- to-many relationship that uniquely identifies a row in the other table ( usually by using the primary key in the second table ) .
reference constraints :
- Parents can check records when inserting a new child record (using foreign key records of children to check master records are almost identical).
- Does not allow modification of foreign keys if the new child records are not represented by his example int parent table .
- can delete all records of children who are almost the same when the parent record is deleted
integrity constraints : it is used to make sure the field ( attribute ) value that is not valid is not allowed .
- can check for multiple values, or the values of certain legal
- can check for NOT NULLtrigger : triggers are strored program database that runs when a specific event terjadi.Triggers can be used to verify the data ( among other things) .
Surrogate key : a key that is used to replace what would be a natural key for the entity .
* Views: refers to the way that different users can view the same database in different
queries stored views ( virtual tables )
views can hide columns ( cleaner , safer )
views can hide table ( cleaner , safer )
views can hide complex operations such as
join - Views can improve query performance.
- concept
- logical
- physical
The concept :
Entities : Objects in which data is collected it can be a person , place , event , or just the concept of a physical object .
External entities : Entities used for the data exchanged, but that is not stored in the database.
Attribute : A unit facts about specific entities : the fact must be atomic ( divided ) .
Relationship: Association among entities .
Business Rules : Policies, procedures or standards that define the organization uses and specific control over data : often implemented in the database as a constraint.
The maximum cardinality : the maximum number of entities can be associated withminimum : the minimum number of entities can be associated withtransferable : relationship transferable if the parents which may change from time to time00:59
Conditional in one direction : means a record that matches may or may not be found on the contact options
Conditional in both directions : means a record that matches may or may not be available on both sides of the relationship
Mandatory in one direction : means matching records must exist in the mandatory relationship
One to many: to show that the records in a table may be related to many ( usually 0 + ) record in the other table .
room: small units called data in the database
- The type of data helps keep dtabase data efficiently.
restict of data attribute values into the correct data type and provides a set of
- Behavior that is consistent with the type of data set ( such as addition, subtraction , etc.untuknombor ) .Unfortunately , different vendors support different data types zoo .
constraints : rules that restrict the values of the data allowed
* Primary key : one or more columns that uniquely identifies a specific row in the table.
- Constraints are duplicate values are not allowed n the primary key column ( s ) table .
- key is usually performed as an index .
indexes speed up searches.
Foreign key : a field -side side a one- to-many relationship that uniquely identifies a row in the other table ( usually by using the primary key in the second table ) .
reference constraints :
- Parents can check records when inserting a new child record (using foreign key records of children to check master records are almost identical).
- Does not allow modification of foreign keys if the new child records are not represented by his example int parent table .
- can delete all records of children who are almost the same when the parent record is deleted
integrity constraints : it is used to make sure the field ( attribute ) value that is not valid is not allowed .
- can check for multiple values, or the values of certain legal
- can check for NOT NULLtrigger : triggers are strored program database that runs when a specific event terjadi.Triggers can be used to verify the data ( among other things) .
Surrogate key : a key that is used to replace what would be a natural key for the entity .
* Views: refers to the way that different users can view the same database in different
queries stored views ( virtual tables )
views can hide columns ( cleaner , safer )
views can hide table ( cleaner , safer )
views can hide complex operations such as
join - Views can improve query performance.
