What is SQL - Its Syntax and Data types

Your Guide to SQL Syntax and Data Types: Unleash the true potential of databases by mastering SQL with ProjectPro

Recipe Objective - What is SQL - Its Syntax and Data types

SQL, which stands for Structured Query Language, is a powerful programming language used for managing and manipulating relational databases. It serves as the foundation for managing data in various database management systems (DBMS) like MySQL, PostgreSQL, Oracle, SQL Server, and more. SQL allows users to interact with databases to perform tasks such as querying, inserting, updating, and deleting data. This recipe will explore the syntax and data types used in SQL, shedding light on its essential components.

What is SQL?

SQL stands for Structured Query Language. It is a domain-specific language used in programming and designed for managing and manipulating data in relational database management systems (RDBMS). SQL provides a comprehensive set of commands that enable users to access and manage data stored in a database. It is widely used across various industries, including but not limited to finance, healthcare, e-commerce, and technology. 

What is SQL used for?

SQL is primarily used for managing and manipulating data stored in relational databases. Some common uses of SQL include:

  • Retrieving data from a database using queries.

  • Inserting new records into a database.

  • Updating existing records in a database.

  • Deleting records from a database.

  • Creating and modifying database schemas.

  • Managing user access and permissions to a database.

  • Performing complex operations such as joins and unions between different database tables.

SQL Syntax 

SQL commands are written in a specific syntax that adheres to a set of rules and guidelines. Here are some fundamental SQL syntax elements:

Statements

SQL statements are instructions given to the database to perform specific actions. Common SQL statements include:

  • SELECT: Retrieves data from one or more database tables.

  • INSERT: Adds new records to a table.

  • UPDATE: Modifies existing data in a table.

  • DELETE: Removes records from a table.

  • CREATE: Creates new database objects like tables, indexes, and views.

  • ALTER: Modifies existing database objects.

  • DROP: Deletes database objects.

Clauses

Clauses are used within SQL statements to filter, sort, or group data. Common SQL clauses include:

  • WHERE: Specifies conditions for selecting or filtering rows.

  • ORDER BY: Sorts the result set based on specified columns.

  • GROUP BY: Groups rows with identical values into summary rows.

  • HAVING: Filters grouped data based on conditions.

  • JOIN: Combines rows from multiple tables based on a related column.

Keywords

SQL includes a set of reserved keywords that are used to construct statements. Some common SQL keywords include SELECT, FROM, WHERE, INSERT, INTO, VALUES, and more.

Identifiers

Identifiers, such as table and column names, are used to reference database objects. They must follow naming rules and conventions and are often enclosed in backticks, double quotes, or square brackets, depending on the DBMS.

Comments

Comments are used to provide explanations within SQL code. Single-line comments start with "--" in most DBMS, and multiline comments are enclosed between "/" and "/."

Note: Every relational database provider does not support all data types. For example, the CLOB data type is not supported by MySQL. You must make it a point to check if the data types are supported when designing database schema and writing SQL queries. The data types listed below do not represent all data types; rather, they are the most often used data types.

SQL Data Types 

SQL data types can be divided into three categories –

  • String

  • Numeric

  • Date and Time

Let us now take a look at each of the data types in SQL –

String Data Type

text – variable-length non-unicode data storage that has a maximum length of 2,147,483,647 characters
char – fixed-length data storage that has a maximum length of 8,000 characters
varchar – variable-length non-unicode data storage that has a maximum length of 8,000 characters
varchar (max) – variable-length non-unicode data storage that has a maximum length of 2E + 31 characters

Numeric Data Type

bit – stores an integer with values either 0 or 1 or NULL
tinyint – stores whole numbers ranging from 0 to 255
smallint – stores numbers ranging from -32,768 and 32,767
int – stores numbers ranging from -2,147,483,648 and 2,147,483,647
bigint – stores numbers ranging from-9,223,372,036, 854,775,808 to 9,223,372,036, 854,775,807
decimal – stores decimal values ranging from -10^38 +1 to 10^38 -1
numeric – stores numbers ranging from -10^38 +1 to 10^38 -1
float – stores floating precision number data from -1.79E+308 to 1.79E+308
real – stores floating precision number data from -3.40E+38 to 3.40E+38

Date and Time Data Type

date – stores date in the format YYYY-MM-DD
time – stores time in the format HH:MM:SS
datetime – stores date and time in the format YYYY-MM-DD HH:MM:SS
timestamp – specifies the timestamp in the format YYYY-MM-DD HH:MM:SS
year – stores year in 4 digit format with values ranging from 1901 to 2155, and 0000

Unicode Data Type

ntext – variable-length unicode data storage that has a maximum length of 1,073,741,823 characters
nchar – fixed-length unicode data storage that has a maximum length of 4,000 characters
nvarchar – variable-length unicode data storage that has a maximum length of 4,000 characters
nvarchar(max) – variable-length unicode data storage that has a maximum length of 2E + 31 characters

Binary Data Type

binary – fixed-length binary data storage that has a maximum length of 8,000 bytes
varbinary – variable-length binary data storage that has a maximum length of 8,000 bytes
varbinary(max) – variable-length binary data storage that has a maximum length of 2E + 31 bytes
image – Variable-length binary data storage that has a maximum length of 2,147,483,647 bytes

Additional data types

ARRAY: Stores arrays of values.

JSON: Stores JSON-formatted data.

XML: Handles XML data.

10 Commonly Asked Questions on Basic SQL Concepts 

Check out the list of the 10 commonly asked questions about basic SQL concepts to help you get started with this essential technology: 

An SQL server is a database management system that stores, manages, and provides access to relational databases. Microsoft SQL Server and MySQL are examples.

A schema in SQL is a logical container for organizing database objects like tables, views, and procedures. It helps in structuring and securing the database.

An SQL database is a structured collection of data stored in tables, using the principles of the SQL language for data management.

SQL stands for Structured Query Language. It's a domain-specific language for managing and querying relational databases.

A foreign key in SQL is a column or set of columns that establishes a link between two tables by referencing the primary key of another table. It enforces referential integrity.

A primary key in SQL is a unique identifier for each record in a table. It ensures data integrity and enforces uniqueness for the table's rows.

SQL injection is a security vulnerability where malicious SQL code is injected into user input, allowing unauthorized access or manipulation of a database.

A trigger in SQL is a set of actions that automatically execute in response to specific events, such as data changes in a table. It's used for enforcing data integrity and automation.

A view in SQL is a virtual table created by a query. It presents data from one or more tables and simplifies complex queries, providing a more convenient way to access data.

A cursor in SQL is a database object that allows for the traversal and manipulation of result sets from a SQL query. It's often used in stored procedures for row-by-row processing.

Master SQL Skills with ProjectPro! 

Understanding SQL, its syntax, and data types is the foundation for effective database management and data manipulation. However, knowledge alone is not enough. To truly master SQL, one must apply this knowledge in practical, real-world scenarios. This is where ProjectPro becomes an invaluable resource. With a vast repository of over 270 projects on SQL, Big Data, and Data Science, ProjectPro provides a platform to hone your SQL skills through hands-on experience. These projects cover a wide range of applications and complexities, enabling you to tackle real challenges and develop a deep understanding of SQL's power and versatility. So, if you're looking to take your SQL skills to the next level, ProjectPro is your ticket to success, offering the opportunity to gain practical experience and expertise in the world of data management.

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