SQL Database Glossary
Our database glossary explains common database terminology and SQL database jargon.
Microsoft Access is an entry-level database management software from Microsoft,
which allows you to organize, access, and share information easily. Access is
very user-friendly and easy to use for inexperienced users, while sophisticated
enough for database and software developers.
ACID short for Atomicity – Consistency – Isolation – Durability and describes
the four properties of an enterprise-level transaction:
ATOMICITY: a transaction should be done or undone completely. In the event of
an error or failure, all data manipulations should be undone, and all data
should rollback to its previous state.
CONSISTENCY: a transaction should transform a system from one consistent state
to another consistent state.
ISOLATION: each transaction should happen independently of other transactions
occurring at the same time.
DURABILITY: Completed transactions should remain
stable/permanent, even during system failure.
Short for Microsoft ActiveX Data Objects. ADO enables your client applications
to access and manage data from a range of sources through an OLE DB provider.
ADO is built on top of OLE DB and its main benefits are ease of use, high
speed, and low memory overhead. ADO makes the task of building complex database
enabled client/server and web applications a breeze.
Database tables are made of different columns (fields) corresponding to the
attributes of the object described by the table.
The COMMIT command in SQL marks the finalization of a database transaction.
Short for Current Set Of Records in some database languages. The cursor is a
database object pointing to a currently selected set of records.
Piece of information collected and formatted in a specific way. The term data
is frequently used to describe binary (machine-readable) information.
A database is a collection of information organized into related tables of data
and definitions of data objects. The data within a database can be easily
accessed and manipulated trough computer program.
DB2 is a relational database management system developed by IBM. DB2 runs on a
variety of platforms including Sun Solaris, Linux and Windows.
dBase is a popular relational database management system produced by
Ashton-Tate corporation in the early 1980s. The dBase format for storing data
has become industry standard and is still in use today.
The DELETE is a SQL command used to delete record(s) from a table in database.
See Column definition
First Normal Form
See Normalization definition
Flat file is a data file that has no structured relationships between its
A foreign key is a key field (column) that identifies records in a table, by
matching a primary key in a different table. The foreign keys are used to
Fourth Normal Form
See Normalization definition
Visual FoxPro is a Microsoft development environment designed for database
An index is a database feature (a list of keys or keywords), allowing searching
and locating data quickly within a table. Indexes are created for frequently
searched attributes (table columns) in order to optimize the database
The INSERT is a SQL command used to add a new record to a table within a
See ACID definition
The JOIN is a SQL command used to retrieve data from 2 or more database tables
with existing relationship based upon a common attribute.
See Primary Key and Foreign Key definitions
Locks are used by Database management systems to facilitate concurrency
control. Locks enable different users to access different records/tables within
the same database without interfering with one another. Locking mechanisms can
be enforced at the record or table levels.
MySQL is an open source relational database management system. MySQL can be
used on various platforms including UNIX, Linux and Windows (there are OLE DB
and ODBC providers as well as .NET native provider for MySQL). MySQL is widely
used as a backend database for Web applications and it' viable and cheaper
alternative to enterprise database systems like MS SQL Server and Oracle.
Normalization is the process of organizing data to minimize redundancy and
remove ambiguity. Normalization involves separating a database into tables and
defining relationships between the tables. There are three main stages of
normalization called normal forms. Each one of those stages increases the level
of normalization. The 3 main normal forms are as follows:
There are 2 more normalization forms, fourth normal form (4NF) and fifth normal
form (5NF), but they are rarely used. Normalization makes databases more
efficient and easier to maintain.
First Normal Form (1NF): Each field in a table must contain different
Second Normal Form (2NF): All attributes that are not dependent upon the
primary key in a database table must be eliminated.
Third Normal Form (3NF): No duplicate information is
permitted. So, for example, if two tables both require a common field, this
common field information should be separated into a different table.
The NULL SQL keyword is used to represent a missing value.
Short for Open DataBase Connectivity, a standard database access technology
developed by Microsoft Corporation. The purpose of ODBC is to allow accessing
any DBMS (DataBase Management System) from any application (as long as the
application and the database are ODBC compliant), regardless of which DBMS is
managing the data. ODBC achieves this by using a middle layer, called a
database driver, between an application and the DBMS. The purpose of this layer
is to transform the application's data queries into commands that the DBMS
understands. As we said earlier, both the application and the DBMS must be ODBC
compliant meaning, the application must be capable of sending ODBC commands and
the DBMS must be capable of responding back to them.
Short for Object Linking and Embedding Data Base. OLE DB is a set of COM-based
interfaces that expose data from a range of sources. OLE DB interfaces give
applications standardized access to data stored in various information sources
like Relational Database Management Systems (MS SQL Server, Oracle, MySQL),
small personal databases like MS Access, productivity tools like spreadsheets;
plain text files, etc. These interfaces support the amount of DBMS
functionality appropriate to the data store, allowing the data store to share
Oracle is an enterprise relational database management system. Oracle's main
rival product MS SQL Server is a low cost alternative offering the same
PostgreSQL is an object-oriented open source relational database management
system, which uses a subset of SQL language.
The primary key of a relational table holds a unique value, which identifies
each record in the table. It can either be a normal field (column) that is
guaranteed to be unique or it can be generated by the database system itself
(GUID or Identity field in MS SQL Server for example). Primary keys may be
composed of more than 1 field (column) in a table.
Queries are the main way to make a request for information from a database.
Queries consist of questions presented to the database in a predefined format,
in most cases SQL (Structured Query Language) format.
The record is a complete set of information presented within a RDBMS. Records
are composed of different fields (columns) in a table and each record is
represented with a separate row in this table.
The ROLLBACK is a SQL command which cancels/undoes the proposed changes in a
pending database transaction and marks the end of the transaction.
See Record definition
Second Normal Form
See Normalization definition
The SELECT is a SQL command, which is the primary means for retrieving data
from a RDBMS.
SQL is short for Structured Query Language and is an industry standard language
used for manipulation of data in a RDBMS. There are several different dialects
of SQL like, ANSI SQL, T-SQL, etc.
Stored Procedure is a set of SQL statements stored within a database server and
is executed as single entity. Using stored procedures has several advantages
over using inline SQL statements, like improved performance and separation of
the application logic layer from database layer in n-tier applications.
A Table in RDBMS refers to data arranged in rows and columns, which defines a
Third Normal Form
See Normalization definition
Transaction is a group of SQL database commands regarded and executed as a
single atomic entity.
Triggers are special type of stored procedures executed automatically when
certain events take place. There are different types of triggers – for update,
for insert and for delete. Each trigger is associated with a single database
The UPDATE is a SQL command used to edit/update existing records in a database
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