Module 1.1: Relational Database Technology

Prelim Topic

Relational Database

• It is a collection of relations or two-dimensional tables.

• Allows tables to be related by means of a common field.

• As few as two tables can be considered a relational database if they share a common field

Table

(Key Terms)

• Basic storage structure

Column

(Key Terms)

• One kind of data in a table

Row

(Key Terms)

• Data for one table instance

Field

(Key Terms)

• The one value found at the intersection of a row and a column

Primary Key

(Key Terms)

• Unique identifier for each row

• Each row of data in a table is uniquely identified by this

Foreign Key

(Key Terms)

• A column that refers to a primary-key column in another table

• You can logically relate data from multiple tables using these

Data Manipulation Language (DML)

(Categories of SQL Statements)

• These statements begin with SELECT, INSERT, UPDATE, DELETE, or MERGE and are used to modify the table data by entering new rows, changing existing rows, or removing existing rows.

Data Definition Language (DDL)

(Categories of SQL Statements)

• These statements create, change, and remove data structures from the database.

• The keywords CREATE, ALTER, DROP, RENAME, TRUNCATE, COMMENT.

Transaction Control Language (TCL)

(Categories of SQL Statements)

• These statements are used to manage the changes made by DML statements.

• Changes to the data are executed using COMMIT, ROLLBACK, and SAVEPOINT

• _ changes can be grouped together into logical transactions

Data Control Language (DCL)

• DCL keywords GRANT and REVOKE are used to give or remove access rights to the database and the structures within it