Skip to main content

Understanding SQL Syntax

Introduction​

Structured Query Language (SQL) is a language designed specifically for communicating with databases. SQL is used to create, maintain, fetch, and manipulate data from relational databases. In this tutorial, we will cover the basics of SQL syntax, which will provide you with the foundation you need to write SQL queries.

SQL Statements​

SQL is made up of statements. Each statement performs a specific task. The most common SQL statements are SELECT, INSERT, UPDATE, DELETE, and CREATE. Every SQL statement ends with a semicolon (;).

Here is a simple example of an SQL statement:

SELECT * FROM Customers;

This statement selects all data from a table named "Customers".

SQL Syntax Rules​

SQL syntax rules are quite similar to the syntax rules of other programming languages. Here are a few key rules:

  1. SQL is not case sensitive: SQL keywords are NOT case sensitive: select is the same as SELECT.

  2. Semicolon is the standard way to separate SQL statements: Each SQL statement must end with a semicolon (;). It is the standard way to separate SQL statements in a database system that supports more than one SQL statement.

  3. Use of whitespace and line breaks: SQL ignores spaces, tabs, and newlines that appear within SQL statements. You can use them freely to format and indent your SQL statements to make them more readable.

SQL Data Types​

SQL supports a variety of data types that you can use in columns when creating tables. These include:

  • CHAR(size): A fixed-length string with a maximum length of size characters.
  • VARCHAR(size): A variable-length string with a maximum length of size characters.
  • INT: A whole number with a maximum value of 2147483647.
  • FLOAT: A floating-point number.
  • DATE: A date.

SQL Operators​

SQL operators are used to perform operations on data within tables. Some of the most common operators include:

  • =: Equal
  • <> or !=: Not equal
  • >: Greater than
  • <: Less than
  • >=: Greater than or equal
  • <=: Less than or equal
  • BETWEEN: Between an inclusive range
  • LIKE: Search for a pattern

Conclusion​

This is just a basic introduction to SQL syntax, but it should give you a solid foundation to start writing your own SQL queries. Remember, the best way to learn is by practice, so try writing some queries on your own and see what you can do!

In upcoming tutorials, we'll dive deeper into each of these aspects of SQL, starting with more in-depth look at SQL statements. Happy learning!