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Table of Contents
1. CONCAT() – Combine Strings Easy
2. SUBSTRING() (or SUBSTR() ) – Extract Part of a String
3. UPPER() and LOWER() – Change Case Consistently
4. TRIM() , LTRIM() , and RTRIM() – Remove Extra Spaces
Home Database Mysql Tutorial What are the most common string functions in MySQL?

What are the most common string functions in MySQL?

Jun 19, 2025 am 12:43 AM
mysql String functions

The most commonly used string functions in MySQL include: 1. CONCAT() is used to concatenate strings, such as merging names or URLs; 2. SUBSTRING() extracts substrings by position and length, suitable for obtaining file extensions, etc.; 3. UPPER() and LOWER() are case-based to standardize comparison or output; 4. TRIM(), LTRIM() and RTRIM() remove spaces to clean up user input data. These functions can efficiently handle the formatting, splicing and cleaning tasks of text data.

What are the most common string functions in MySQL?

When working with text data in MySQL, there are several string functions that you'll find yourself using over and over. These functions help manipulate, format, and extract information from string values ??efficiently. While there's a wide range of options available, some stand out due to their frequency of use and practice.

1. CONCAT() – Combine Strings Easy

If you need to join two or more strings together, CONCAT() is your go-to function. It takes multiple arguments and returns a single concatenated string.

For example:

 SELECT CONCAT('Hello', ' ', 'World'); -- Returns 'Hello World'

You might use this when combining first and last names into a full name, or building URLs from different parts. Just keep in mind that if any of the inputs are NULL , the whole result becomes NULL . To avoid that, pair it with IFNULL() when needed.

2. SUBSTRING() (or SUBSTR() ) – Extract Part of a String

This function lets you pull out a portion of a string based on position and length. The basic syntax is:

 SUBSTRING(str, start_position, length)

Example:

 SELECT SUBSTRING('abcdefg', 3, 2); -- Returns 'cd'

It's handy for extracting things like file extensions from filenames or codes from longer identifiers. One thing to note:

  • If start_position is negative, it counts backward from the end.
  • If length is omitted, it grabs everything from the start position to the end.

3. UPPER() and LOWER() – Change Case Consistently

These are simple but essential for normalizing string comparisons or outputs. As their names suggest:

  • UPPER() converts a string to uppercase.
  • LOWER() converts it to lowercase.

Use them when comparing user input that might vary in case, or when displaying data in a consistent format.

Examples:

 SELECT UPPER('hello'); -- Returns 'HELLO'
SELECT LOWER('WORLD'); -- Returns 'world'

They don't modify non-alphabetical characters, so numbers and symbols stay the same.

4. TRIM() , LTRIM() , and RTRIM() – Remove Extra Spaces

Whitespace can cause issues in comparisons or display. That's where these trimming functions come in:

  • TRIM() removes spaces from both ends.
  • LTRIM() removes only leading spaces.
  • RTRIM() removes only trailing spaces.

Example:

 SELECT TRIM(' Hello World '); -- Returns 'Hello World'

They're especially useful when cleaning up user-submitted data before inserting or comparing values.


These are just a few of the most commonly used string functions in MySQL. They cover a lot of ground when it comes to formatting, combining, and cleaning text data. There's more to explore, but mastering these will handle most day-to-day tasks involving strings.

Basically that's it.

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