Represents one entity set, e.g. a Students table stores every student in the school.
Tables are unordered, a DBMS can physically store rows anywhere as long as the logical structure is preserved.
Record (tuple / row):
One horizontal line of data inside a table.
Integrity rules (such as NOT NULL or CHECK) are validated at the record level when it is inserted or updated.
Example
Contains all attribute values describing a single entity instance, for example, Student #1024’s name, birth‑date and grade.
Field (attribute / column)
Vertical slice specifying a single data item (e.g., Email VARCHAR (100)).
Every record supplies one atomic value for the field, drawn from the column’s defined data type and domain.
Columns can carry constraints (default values, uniqueness) and metadata (comments, collation, masks).
Primary key
Column(s) chosen to uniquely label each record, cannot be NULL.
Guarantees entity integrity and is automatically indexed, speeding joins and searches.
Other tables reference it through foreign keys (e.g., StudentID in Students).
Secondary key (alternate / secondary index)
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What is Database?
A database is an organized collection of structured information, or data, typically stored electronically in a computer system. Databases are designed to manage large amounts of information efficiently and allow users to retrieve, update, and manipulate data easily.
DefinitionDatabaseA structured collection of data that is stored and accessed electronically from a computer system.AnalogyThink of a database like a digital filing cabinet where each drawer represents a table, and each file within the drawer represents a record.ExampleA library database might contain tables for books, authors, and borrowers, allowing librarians to quickly find information about any book or borrower.
