Database Concepts Essay

3232 WordsMay 4, 201213 Pages
FUNDAMENTAL DATABASE CONCEPTS Data Hierarchy in a Database (from lowest to the highest level) Bits: 0/1; basically, the only language understood by a computer; represented by the strength of current, magnetic polarity, or some other method. Bytes (Characters): Group of bits (normally 7 or 8 bits to a byte) that represent alphanumeric characters (a,b,c…1,2,3…)and special symbols (#,@,$…). Field (Attribute or Column): Group of characters that represent a field (name, social security number, address, etc.). ** In a relational database management system, such as Access or Oracle, the term COLUMN is used interchangeably with attribute or field. Record: A group of related fields (e.g., a specific student’s social security number, name, address, major, etc.). File (Table): A group of related records (e.g., a file containing records of students, or a file containing records of faculty). We will not keep students’ and faculty’s records in a single file because a file should not contain unrelated records. ** A table is typically shown as: table_name(column_name, column_name……). And also we use an abbreviation of the table name with the column names. For example, in a student table, we may name student’s ssn as std_ssn. This way, we can tell what table a particular column appears in. Database: A group of related files (a database of students, a database of administrators, a database of faculty, etc.). Creating different databases helps effective administration and management of these databases. For example, different database administrators (DBAs) may be assigned the responsibility of administering and managing different databases. Entity Person, place, thing, event, etc., on which we keep information. For instance, we keep information on students, faculty, courses and classes. For each entity in our database, we create at least one table for it.

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