Oracle CONCAT Function: A Comprehensive Guide to String Concatenation

The CONCAT function in Oracle SQL is a fundamental tool for combining multiple strings into a single, cohesive string. This guide will walk you through its syntax and provide practical examples to help you effectively concatenate data within your Oracle database queries.

Understanding the CONCAT Function Syntax

The basic syntax for the CONCAT function is straightforward:

SELECT CONCAT(string1, string2) FROM table_name;

It takes two string arguments and returns a single string that is the result of concatenating them. If you need to concatenate more than two strings, you can nest CONCAT functions or use the concatenation operator (||).

Practical Examples of Oracle CONCAT

Example 1: Combining First and Last Names

Let’s say you have an employees table with first_name and last_name columns, and you want to display a full name. You can achieve this using CONCAT:

SELECT CONCAT(first_name, ' ' || last_name) AS full_name FROM employees;

In this example, we concatenate the first_name, a space, and the last_name to create a full_name alias. Note the use of || for concatenating the space and last_name, demonstrating an alternative to nesting CONCAT for multiple strings.

Example 2: Concatenating Literal Strings and Column Values

You can also combine literal strings with column values:

SELECT CONCAT('Employee ID: ', employee_id) AS employee_info FROM employees;

This query would return results like “Employee ID: 101”, “Employee ID: 102”, and so on.

Conclusion

The Oracle CONCAT function is an essential tool for data manipulation, allowing you to easily combine string data from various sources within your SQL queries. By mastering its usage, you can present your data in a more readable and meaningful format.