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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.
West Yorkshire is a metropolitan and ceremonial county in England. It is an inland and, in relative terms, upland county having eastward-draining valleys while taking in the moors of the Pennines. West Yorkshire came into existence as a metropolitan county in 1974 after the passage of the Local Government Act 1972[2] and has a population of 2.3 million.
West Yorkshire consists of five metropolitan boroughs (City of Bradford, Calderdale, Kirklees, City of Leeds and City of Wakefield) and is bordered by the counties of Derbyshire to the south, Greater Manchester to the south-west, Lancashire to the west and north-west, North Yorkshire to the north and east, and South Yorkshire to the south and south-east.
Remnants of strong coal, wool and iron ore industries remain in the county, having attracted people over the centuries, and this can be seen in the buildings and architecture. Major railways and two major motorways traverse the county, which also contains Leeds Bradford International Airport.
West Yorkshire includes the West Yorkshire Urban Area, which is the biggest and most built-up urban area within the historic county boundaries of Yorkshire.
