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Description

This error signifies an issue within a regular expression pattern where a quantifier interval `{min,max}` is defined incorrectly. Specifically, it means the 'maximum' value provided is numerically less than the 'minimum' value, which is logically impossible for a range. This typically occurs when using MySQL's regular expression functions like `REGEXP_LIKE`, `REGEXP_REPLACE`, or `REGEXP_SUBSTR` with a malformed quantifier.

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Error Message

The maximum is less than the minumum in a {min,max} interval.

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Known Causes

3 known causes

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Incorrect Quantifier Syntax

The most common cause is defining a regular expression quantifier like `{5,3}` where the minimum value (5) is greater than the maximum value (3) in the interval.

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Dynamic Pattern Generation Error

When constructing regular expression patterns programmatically (e.g., in application code), variables used for `min` and `max` might be swapped or assigned incorrect values, resulting in an invalid interval.

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Typographical Error

A simple manual entry mistake or typo when writing the regular expression pattern can easily reverse the order of minimum and maximum values within a quantifier interval.

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Solutions

3 solutions available

1. Correct Quantifier Range in REGEXP easy

Adjust the min and max values in your REGEXP quantifier to be valid.

1

Identify the specific `REGEXP` or `RLIKE` expression that is causing the error. This is usually found in a `WHERE` clause or a `CASE` statement.

Example of problematic regex: `WHERE column_name REGEXP 'a{5,2}'`

2

Modify the quantifier `{min,max}` so that `min` is less than or equal to `max`. If you intend for the character to appear at least 5 times and at most 2 times, this is impossible. You likely meant `a{2,5}` (at least 2, at most 5) or `a{5,}` (at least 5).

Corrected example: `WHERE column_name REGEXP 'a{2,5}'` or `WHERE column_name REGEXP 'a{5,}'`

3

Re-run the SQL query after correcting the regex pattern.

2. Review and Simplify Complex Regex Patterns medium

Break down or simplify overly complex regular expressions to avoid range errors.

1

Examine the `REGEXP` or `RLIKE` pattern for parts that might be inadvertently creating an invalid quantifier range. This often happens with nested quantifiers or complex character sets.

Consider a pattern like `(a{3,5}){2,1}`. The inner `{3,5}` is valid, but the outer `{2,1}` is not.

2

If the pattern is very long or intricate, consider using a tool or online regex debugger to analyze its structure and identify the problematic quantifier.

3

Rewrite the regex to be more straightforward. For instance, instead of nested quantifiers, you might be able to express the same logic with a single, correctly defined quantifier.

If the intention was to match 'aa' repeated 2 to 5 times, `(aa){2,5}` is correct. If it was to match 'a' repeated 4 to 10 times, `a{4,10}` is the simpler and correct form.

4

Test the simplified regex thoroughly to ensure it still matches the intended data.

3. Validate User-Supplied Regex Input advanced

Implement server-side validation for any regex patterns provided by users.

1

If your application allows users to input regular expressions that are then used in MySQL queries, implement validation logic in your application code (e.g., backend language like PHP, Python, Java).

Example in Python (conceptual):

2

Before constructing the SQL query, parse the user-provided regex. Check for common errors like invalid quantifier ranges.

python
import re

def is_valid_regex(pattern):
    try:
        # Attempt to compile the regex. This will catch many syntax errors.
        re.compile(pattern)
        # Further checks for specific invalid ranges can be added here if needed.
        # For example, a more robust check could involve parsing the regex structure.
        return True
    except re.error as e:
        print(f"Invalid regex: {e}")
        return False

user_regex = input("Enter your regex: ")
if not is_valid_regex(user_regex):
    print("Please enter a valid regular expression.")
    # Handle the error, perhaps by not executing the query or showing an error message.
else:
    # Proceed to build and execute the SQL query with user_regex
    pass

3

If the regex is invalid, return an informative error message to the user and do not proceed with executing the SQL query.

4

If the regex is valid, then safely incorporate it into your MySQL query.

Example SQL construction (conceptual):

5

Use prepared statements or proper escaping mechanisms when inserting the validated regex into the SQL query to prevent SQL injection vulnerabilities.

sql
SET @user_regex = 'your_validated_regex_here';
SELECT * FROM your_table WHERE your_column REGEXP @user_regex;

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Related Errors

5 related errors

MySQL Error 3693: Invalid Regex Quantifier Range