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SQL
SQL Meaning
SQL (Structured Query Language)is a specialized programming language designed for managing and manipulating data stored in relational databases. It allows users to perform various operations such as querying, updating, inserting, and deleting data efficiently12.
Key Principles of SQL
Declarative Language: SQL is a declarative language, meaning it specifies what data to retrieve or manipulate rather than how to perform the operation. This makes it easier to use and understand1.
Standardization: SQL became a standard of the American National Standards Institute (ANSI) in 1986 and the International Organization for Standardization (ISO) in 19872.
Components: SQL consists of several sublanguages, including Data Query Language (DQL), Data Definition Language (DDL), Data Control Language (DCL), and Data Manipulation Language (DML)1.
Common SQL Commands
SELECT: Retrieves data from a database.
INSERT: Adds new records to a database.
UPDATE: Modifies existing records.
DELETE: Removes records from a database.
CREATE: Creates new database objects like tables and views.
ALTER: Modifies existing database objects.
Example of a Simple SQL Query
SELECT*FROMCustomersWHERECustomerNameLIKE'J%'ORDER BYCustomerIDDESCLIMIT 10;
This query retrieves the top 10 customers whose names start with 'J', ordered in descending order by their customer ID3.
Uses of SQL
SQL is widely used across various industries and applications, including:
Data Retrieval: Extracting data from databases for analysis and reporting.
Data Manipulation: Adding, updating, and deleting data in databases.
Data Definition: Defining the structure and organization of data in databases.
Access Control: Managing user permissions and ensuring data security23.
Important Considerations
Interoperability: SQL implementations can vary between different database systems, leading to compatibility issues1.
Security: SQL injection is a common security vulnerability where malicious SQL code is inserted into queries to manipulate or corrupt data3.
In conclusion, SQL is a powerful and versatile language for managing relational databases, offering a wide range of functionalities for data manipulation, retrieval, and security12.
North Wales (Welsh: Gogledd Cymru), also known as the North of Wales (or simply the North, or in Welsh 'y Gogledd' in Wales), is a geographic region of Wales, encompassing its northernmost areas. It borders Mid Wales (or South Wales under some definitions) to the south, England to the east, and the Irish Sea to the north and west. The area is highly mountainous and rural, with Snowdonia National Park (Parc Cenedlaethol Eryri) and the Clwydian Range, known for its mountains, waterfalls and trails, located wholly within the region. Its population is more concentrated in the north-east, and northern coastal areas of the region, whilst significant Welsh-speaking populations are situated in its western and rural areas. North Wales is imprecisely defined, lacking any exact definition or administrative structure. For the public purposes of health, policing and emergency services, and for statistical,[1] economic[2][3] and cultural[note 2][4] purposes, North Wales is commonly defined administratively as its six most northern principal areas, but other definitions of the geographic region exist, with Montgomeryshire historically considered to be part of the region.
Those from North Wales are sometimes referred to as "Gogs" (from "Gogledd" – the Welsh word for "north");[5] in comparison, those from South Wales are sometimes called "Hwntws" by those from North Wales.
The region includes the localities of Wrexham, Deeside, Rhyl, Colwyn Bay, Flint, Bangor, Llandudno, and Holyhead. The largest localities in North Wales are the town of Wrexham and the conurbations of Deeside and Rhyl/Prestatyn, where the main retail, cultural, educational, tourism, and transport infrastructure and services of North Wales are located.
