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DATA IN THE SCHEME OF THINGS
DATA IS:
Any small slice of information.
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INFORMATION IS:
Created when there are several pieces of data arranged together.
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KNOWLEDGE IS:
Created when information is grouped together.
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MANAGING DATA:
IN ORDER TO MANAGE DATA:
We have to store it.
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WE STORE DATA FOR:
Many reasons:
- Historical fact.
- Inventory.
- Temporary calculations.
- Business intelligence.
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WE MANAGE THE STORAGE OF THE INFORMATION SO THAT:
We can ask for it in many different ways.
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WHAT IS A DATABASE?
THE ENTIRE COLLECTION OF DATA IS CALLED:
A Database.
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A DATABASE IS AN ORDERED COLLECTION OF INFORMATION FROM WHICH:
A computer program can quickly access information.
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EACH ROW IN A DATABASE IS CALLED:
A Record.
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A RECORD IN A DATABASE IS A:
Single complete set of related information.
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EACH COLUMN IN A DATABASE TABLE IS CALLED:
A Field.
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FIELDS ARE:
The individual categories of information stored in a record.
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TYPES OF DATABASES:
FLAT-FILE DATABASES:
Store information in a single table.
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RELATIONAL DATABASES:
Store information across multiple related tables:
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MULTI-DIMENSIONAL DATABASES:
Use either collections of relational databases or treats data groups as objects that can be viewed from many “angles”.
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FLAT-FILE DATABASES:
EXAMPLES ARE:
- Plain text files.
- CSV (comma separated values).
- XML files.
- JSON strings.
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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.
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EFFICIENCY DEPENDS ON THE METHOD AND THE:
Operating system:
- Unix is very efficient with flat files,
- Windows (NTFS and FAT) is not.
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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)
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DATABASE MANAGEMENT SYSTEMS:
A DATABASE MANAGEMENT SYSTEM (OR DBMS) IS AN:
Application or collection of applications used to access and manage a database.
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A SCHEMA IS:
The structure of a database including its tables, fields, and relationships.
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A RELATIONAL DATABASE MANAGEMENT SYSTEM (OR RDBMS) IS:
A system that stores data in a relational format.
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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
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RELATIONAL DATABASES PROVIDE:
Much broader support for the storage and access of information.
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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.
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RELATIONAL DATABASES HAVE THEIR OWN:
Special needs and their own unique programmatic requirements.
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EXAMPLES OF RDBMS SYSTEMS ARE:
- Microsoft Excel and Microsoft Access.
- MySQL.
- MaxDB14.
- Microsoft SQL Server.
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UNDERSTANDING RELATIONAL DATABASES:
RELATIONAL DATABASES CONSIST OF:
One or more related tables.
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A PRIMARY TABLE IS:
The main table in a relationship that is referenced by another table.
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A RELATED TABLE (or “child table”) REFERENCES:
A primary table in a relational database.
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A PRIMARY KEY IS A FIELD THAT CONTAINS A:
unique identifier for each record in a primary table.
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A PRIMARY KEY IS:
A type of index which identifies records in a database to make retrievals and sorting faster.
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PRIMARY KEYS, NO MATTER WHAT DATA TYPE THEY ARE:
May only exist once within a table.
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PRIMARY KEYS CAN BE:
A single field or several fields in combination, but they must be in a single table.
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A FOREIGN KEY IS:
A field in a related table that refers to the primary key in a primary table.
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PRIMARY AND FOREIGN KEYS:
Link records across multiple tables in a relational database.
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ONE-TO-ONE RELATIONSHIPS:
A ONE-TO-ONE RELATIONSHIP EXISTS:
Between two tables when a related table contains exactly one record for each record in the primary table.
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CREATE A ONE-TO-ONE RELATIONSHIP TO:
Break information into multiple, logical sets.
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INFORMATION IN THE TABLES IN A ONE-TO-ONE RELATIONSHIP CAN:
Be placed within a single table.
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ONE-TO-ONE RELATIONSHIPS:
Make the information in one of the tables confidential and accessible only by certain individuals.
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ONE-TO-MANY RELATIONSHIPS:
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.
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BREAKING TABLES INTO MULTIPLE RELATED TABLES TO REDUCE REDUNDANT ANDDUPLICATE INFORMATION IS CALLED:
Normalization.
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NORMALIZATION IN A ONE-TO-MANY RELATIONSHIP
PROVIDE:
A more efficient and less redundant method of storing this information in a database.
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MANY-TO-MANY RELATIONSHIPS:
A MANY-TO-MANY RELATIONSHIP EXISTS IN A RELATION DATABASE WHEN:
Many records in one table are related to many records in another table.
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A JUNCTION TABLE CREATES A:
One-to-many relationship for each one to of the two tables in a many-to-many relationship.
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A JUNCTION TABLE CONTAINS:
Foreign keys from the two tables.
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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.
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AN ENTITY IS AN OBJECT – JUST LIKE:
In HTML- Depicted with a rectangle.
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AN ATTRIBUTE IS CHARACTERISTIC OF:
An entity:
- 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.
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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.
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AN ATTRIBUTE AND COMPOSITE ATTRIBUTES ARE:
Tied to its entity or sub-attributes by connectors.
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KEYS ARE ATTRIBUTES THAT DEFINE UNIQUENESS AND ARE:
Designated with an underline.
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REPRESENTING RELATIONSHIPS WITH ER:
MULTIPLE ENTITY STRUCTURES ARE TIED TO OTHER ENTITY STRUCTURES WITH A RELATIONSHIP, ARE SIGNIFIED BY A:
Diamond.
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RELATIONSHIPS CAN BE:
Optional or Compulsory depending on the type of the database.
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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.
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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
- store?
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RELATIONSHIPS CAN ALSO HAVE:
Attributes.
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ACCESSING RDBMS DATA:
A QUERY IS A:
Structured set of instructions and criteria for retrieving, adding, modifying, and deleting database information.
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STRUCTURED QUERY LANGUAGE (OR SQL) IS A:
Standard data manipulation language used among many database management systems.
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EACH RDBMS HAS IT’S OWN:
SQL.
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MOST SQL CONFORMS LARGELY TO A:
Basic SQL standard.
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OPEN DATABASE CONNECTIVITY (OR ODBC) ALLOWS:
ODBC compliant applications to access any data source for which there is an ODBC driver.
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