MySQL Unique Fields: How to Handle Trailing Spaces?

MySQL Database with Unique Fields: Ignoring Ending Spaces

When working with MySQL databases, you may encounter an issue where unique fields ignore ending spaces. This can occur when you need to store input with varying spacing on the left or right of words, but the database automatically trims the trailing spaces.

This issue stems from MySQL's default handling of strings, which ignores trailing whitespace during comparisons. To understand this behavior, consider the following:

<br>VARCHAR my_field UNIQUE NOT NULL;<br>

If you insert 'apple' and ' apple' (with trailing space) into this field, the unique check will fail because MySQL treats both values as identical.

Possible Solutions:

1. Store Values as VARBINARY:
   Convert the input to VARBINARY to preserve the exact byte pattern, including trailing spaces.

<br>ALTER TABLE my_table MODIFY my_field VARBINARY(255) UNIQUE;<br>

2. Use NO PAD Collations (MySQL 8.0 ):
   MySQL 8.0 and above supports collations with the NO PAD attribute, which preserves trailing spaces in string comparisons.

<br>CREATE TABLE my_table (<br>  my_field VARCHAR(255) UNIQUE COLLATE utf8mb4_0900_ai_ci<br>);<br>

3. Custom Collation (Not Recommended):
   You can create a custom collation with the NO PAD attribute, but this is not recommended as it can introduce compatibility issues.

Conclusion:

By understanding the default behavior of MySQL and implementing the appropriate solutions, you can ensure that your unique fields handle trailing spaces as desired.

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