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DATA IN THE SCHEME OF THINGS
Any small slice of information.
Created when there are several pieces of data arranged together.
Created when information is grouped together.
IN ORDER TO MANAGE DATA:
We have to store it.
WE STORE DATA FOR:
- Historical fact.
- Temporary calculations.
- Business intelligence.
WE MANAGE THE STORAGE OF THE INFORMATION SO THAT:
We can ask for it in many different ways.
WHAT IS A DATABASE?
THE ENTIRE COLLECTION OF DATA IS CALLED:
A DATABASE IS AN ORDERED COLLECTION OF INFORMATION FROM WHICH:
A computer program can quickly access information.
EACH ROW IN A DATABASE IS CALLED:
A RECORD IN A DATABASE IS A:
Single complete set of related information.
EACH COLUMN IN A DATABASE TABLE IS CALLED:
The individual categories of information stored in a record.
TYPES OF DATABASES:
Store information in a single table.
Store information across multiple related tables:
Use either collections of relational databases or treats data groups as objects that can be viewed from many “angles”.
- Plain text files.
- CSV (comma separated values).
- XML files.
- JSON strings.
FLAT-FILE STORAGE IS EFFICIENT UP TO A POINT:
- If your data requirements are small, flat files are more efficient.
- Does not require an application or middleware.
EFFICIENCY DEPENDS ON THE METHOD AND THE:
- Unix is very efficient with flat files,
- Windows (NTFS and FAT) is not.
FLAT-FILE DATA ARRANGEMENT:
SUPPOSE YOU NEEDED TO STORE A SIMPLE DATA COLLECTION OF STUDENT NAMES, ID NUMBERS AND EMAILS:
For such a data collection, something very linear in nature, a flat file is more efficient, unless there are a large number of data points. (records)
DATABASE MANAGEMENT SYSTEMS:
A DATABASE MANAGEMENT SYSTEM (OR DBMS) IS AN:
Application or collection of applications used to access and manage a database.
A SCHEMA IS:
The structure of a database including its tables, fields, and relationships.
A RELATIONAL DATABASE MANAGEMENT SYSTEM (OR RDBMS) IS:
A system that stores data in a relational format.
RELATIONAL DATABASE MANAGEMENT SYSTEMS:
RELATIONAL DATABASE MANAGEMENT SYSTEMS (RDBMS) ARE:
Applications (middleware) that serve several purposes*:
- Storage of data with preservation of file structure (schema).
- Provide access to data through SQL or some other language(querying capability).
- Provide security over the access of data.
- Provide backups.
- Provide availability of programmatic control.
- Provide wide-scale up-time.
* Not all apply in every case
RELATIONAL DATABASES PROVIDE:
Much broader support for the storage and access of information.
ONCE YOU HAVE MORE THAN ON FLAT-FILE, PARTICULARLY IF THAT DATA IS EITHER RELATED OR SUBJECT TO DUPLICATION:
A Relational Database should be used.
RELATIONAL DATABASES HAVE THEIR OWN:
Special needs and their own unique programmatic requirements.
EXAMPLES OF RDBMS SYSTEMS ARE:
- Microsoft Excel and Microsoft Access.
- Microsoft SQL Server.
UNDERSTANDING RELATIONAL DATABASES:
RELATIONAL DATABASES CONSIST OF:
One or more related tables.
A PRIMARY TABLE IS:
The main table in a relationship that is referenced by another table.
A RELATED TABLE (or “child table”) REFERENCES:
A primary table in a relational database.
A PRIMARY KEY IS A FIELD THAT CONTAINS A:
unique identifier for each record in a primary table.
A PRIMARY KEY IS:
A type of index which identifies records in a database to make retrievals and sorting faster.
PRIMARY KEYS, NO MATTER WHAT DATA TYPE THEY ARE:
May only exist once within a table.
PRIMARY KEYS CAN BE:
A single field or several fields in combination, but they must be in a single table.
A FOREIGN KEY IS:
A field in a related table that refers to the primary key in a primary table.
PRIMARY AND FOREIGN KEYS:
Link records across multiple tables in a relational database.
A ONE-TO-ONE RELATIONSHIP EXISTS:
Between two tables when a related table contains exactly one record for each record in the primary table.
CREATE A ONE-TO-ONE RELATIONSHIP TO:
Break information into multiple, logical sets.
INFORMATION IN THE TABLES IN A ONE-TO-ONE RELATIONSHIP CAN:
Be placed within a single table.
Make the information in one of the tables confidential and accessible only by certain individuals.
A ONE-TO-MANY RELATIONSHIP EXISTS IN:
A relational database when one record in a primary table has many related records in a related table.
BREAKING TABLES INTO MULTIPLE RELATED TABLES TO REDUCE REDUNDANT ANDDUPLICATE INFORMATION IS CALLED:
NORMALIZATION IN A ONE-TO-MANY RELATIONSHIP
A more efficient and less redundant method of storing this information in a database.
A MANY-TO-MANY RELATIONSHIP EXISTS IN A RELATION DATABASE WHEN:
Many records in one table are related to many records in another table.
A JUNCTION TABLE CREATES A:
One-to-many relationship for each one to of the two tables in a many-to-many relationship.
A JUNCTION TABLE CONTAINS:
Foreign keys from the two tables.
DESIGNING DATA STRUCTURES WITH ER:
ENTITY RELATIONSHIP (OR ER) DIAGRAMS:
Are a method used to construct data layouts by providing a visual depicting the association of data.
AN ENTITY IS AN OBJECT – JUST LIKE:
In HTML- Depicted with a rectangle.
AN ATTRIBUTE IS CHARACTERISTIC OF:
- Depicted with an oval.
- Can be many attributes for a single entity.
- Attributes can be multi-value, indicated by a double oval.
- Composite attributes are attributes made of a collection of other attributes.
DESIGNING DATA STRUCTURES WITH ER:
-IN AN ER, ATTRUBUTES OF AN ENTITY ARE:
Tied to it with connectors and the attributes defined inside the attribute shape.
AN ATTRIBUTE AND COMPOSITE ATTRIBUTES ARE:
Tied to its entity or sub-attributes by connectors.
KEYS ARE ATTRIBUTES THAT DEFINE UNIQUENESS AND ARE:
Designated with an underline.
REPRESENTING RELATIONSHIPS WITH ER:
MULTIPLE ENTITY STRUCTURES ARE TIED TO OTHER ENTITY STRUCTURES WITH A RELATIONSHIP, ARE SIGNIFIED BY A:
RELATIONSHIPS CAN BE:
Optional or Compulsory depending on the type of the database.
DOES THE EXISTENCE OF ONE REQUIRE THE EXISTENCE OF THE OTHER?
IN TOTAL PARTICIPATION:
One entity can exist in the relationship by attachment to the other.
IN PARTIAL PARTICIPATION:
One entity can exist without having relationship to the other.
- Example: is a person in a store a customer because he buys something or just because he walks into a
RELATIONSHIPS CAN ALSO HAVE:
ACCESSING RDBMS DATA:
A QUERY IS A:
Structured set of instructions and criteria for retrieving, adding, modifying, and deleting database information.
STRUCTURED QUERY LANGUAGE (OR SQL) IS A:
Standard data manipulation language used among many database management systems.
EACH RDBMS HAS IT’S OWN:
MOST SQL CONFORMS LARGELY TO A:
Basic SQL standard.
OPEN DATABASE CONNECTIVITY (OR ODBC) ALLOWS:
ODBC compliant applications to access any data source for which there is an ODBC driver.