SQL String Functions From Basics to Advanced

When you’re working with databases, sooner or later you’ll face the need to clean, combine, or analyze textual data. That’s where SQL string functions step in—I learned this through years of writing queries, and today, I’ll walk you through them so you can level up your database skills too.

Starting with the Basic SQL String Functions

First, if this is your first foray into SQL, you’ll want to know how to write a basic query. I recommend you start with SQL – Structured Query Language: Basics of SQL for a strong foundation.

1. CONCAT: Joining Strings Together

Suppose you want to join a user’s first and last names into a single full name. In SQL, you do this using CONCAT().

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

This example combines two string columns with a space, giving you the user’s full name.

Want more on string combination? Dive into the details with MySQL CONCAT() AND CONCAT_WS() functions.

2. LENGTH: Counting Characters

Sometimes you need to find out how long a particular value is. Here’s how you count the characters:

SELECT name, LENGTH(name) AS name_length FROM products;

This query returns each product’s name and the number of characters it contains.

3. SUBSTRING / SUBSTR: Extracting Part of a String

If you want just a piece of a string—for instance, taking the first three letters of a product code—you’d use SUBSTRING():

SELECT SUBSTRING(product_code, 1, 3) AS prefix FROM items;

This picks out the first three characters of every product_code in the items table. Super handy for code prefixes!

4. UPPER & LOWER: Changing Case

Data’s not always case-consistent. To standardize everything to uppercase (or lowercase), use UPPER() or LOWER():

SELECT UPPER(email) as email_upper FROM customers;

You get all your email addresses in uppercase—perfect for comparisons!

Now, level up with String Functions for the intermediate level

By now, you can combine and analyze strings. Now let’s look at pattern matching and replacements.

5. REPLACE: Swapping Text

What if you need to swap part of a string? Here’s an answer:

SELECT REPLACE(description, 'outdated', 'new') FROM info;

In this query, every instance of “outdated” is replaced with “new” in the description field.

6. LOCATE / INSTR: Finding Positions

To find where a substring appears inside a string:

SELECT LOCATE('sql', article_title) as position FROM articles;

You’ll get the starting position of the word “SQL” in each article title. Zero means not found.

7. TRIM: Cleaning Up Spaces

Remove unwanted spaces at the beginning and end of your data:

SELECT TRIM('  hello world  ') AS clean_text;

Result: ‘hello world’—no extra spaces!

Expert Techniques

Ready to combine these skills for real-world data engineering tasks? Here’s how you can use them in advanced scenarios.

Using String Functions for Dynamic SQL and Pagination

For complex text manipulations and paginated output, you’ll want to understand not only string operations but also SQL optimization and pagination logic. Here are some great next reads from TechBriefers:

• Concept of pagination by SQL Query in MySQL (Learn how to break big results into smaller chunks with SQL)
• Optimize Slow MySQL Queries – Top 10 Ways With Examples (Tips for improving query speed—even with string operations!)

Why SQL String Functions Matter

When I started out, string functions felt advanced—but little by little, you get comfortable. Today you saw how CONCAT, SUBSTRING, REPLACE, and other functions streamline text data, making you a more effective developer.

If you found these tips useful, share your own string function stories—or check out more SQL tricks in our MySQL articles and tutorials collection to keep learning.

Happy querying—I’m here to help you keep leveling up!