## How Does MySQL Handle Umlauts in Unicode Collations?

MySQL Unicode Collations: Understanding Umlaut Equivalence

The observation that MySQL considers "åäö" equivalent to "AAO" is rooted in the use of non-language-specific Unicode collations. As stated in the MySQL documentation, collations of this type standardize the handling of Unicode characters, including umlauts.

Specifically, in collations such as utf8_general_ci and utf8_unicode_ci, the following equalities apply:

• Ä = A
• Ö = O
• Ü = U

This "feature" ensures that comparisons and searches treat certain characters as equivalent, regardless of their specific Unicode code points.

To mitigate this issue, you have two primary options:

• Use a Collation without Umlaut Equivalence: Opt for a collation like utf8_bin, which maintains distinct representations for these characters. However, be aware that this may lead to other limitations.
• Override Collation for Query: Utilize a different collation specifically for the query. By appending COLLATE to the query, you can define the desired collation for the comparison. For example:

select * from topics where name='Harligt' COLLATE utf8_bin;

It's important to note that achieving case-insensitive searches while preserving umlaut distinction is more complex. If a suitable MySQL collation exists that meets these criteria, its existence would be of interest.

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