Example 1: Sorting German Umlauts

Suppose that column X in table T has these latin1 column values:

Muffler
Müller
MX Systems
MySQL

Suppose also that the column values are retrieved using the following statement:

SELECT X FROM T ORDER BY X COLLATE collation_name;

The following table shows the resulting order of the values if we use ORDER BY with different collations.

The character that causes the different sort orders in this example is the U with two dots over it (ü), which the Germans call “U-umlaut.”

Example 2: Searching for German Umlauts

Suppose that you have three tables that differ only by the character set and collation used:

mysql> SET NAMES utf8;
mysql> CREATE TABLE german1 (
         c CHAR(10)
       ) CHARACTER SET latin1 COLLATE latin1_german1_ci;
mysql> CREATE TABLE german2 (
         c CHAR(10)
       ) CHARACTER SET latin1 COLLATE latin1_german2_ci;
mysql> CREATE TABLE germanutf8 (
         c CHAR(10)
       ) CHARACTER SET utf8 COLLATE utf8_unicode_ci;

Each table contains two records:

mysql> INSERT INTO german1 VALUES ('Bar'), ('Bär');
mysql> INSERT INTO german2 VALUES ('Bar'), ('Bär');
mysql> INSERT INTO germanutf8 VALUES ('Bar'), ('Bär');

Two of the above collations have an A = Ä equality, and one has no such equality (latin1_german2_ci). For that reason, you'll get these results in comparisons:

mysql> SELECT * FROM german1 WHERE c = 'Bär';
+------+
| c    |
+------+
| Bar  |
| Bär  |
+------+
mysql> SELECT * FROM german2 WHERE c = 'Bär';
+------+
| c    |
+------+
| Bär  |
+------+
mysql> SELECT * FROM germanutf8 WHERE c = 'Bär';
+------+
| c    |
+------+
| Bar  |
| Bär  |
+------+

This is not a bug but rather a consequence of the sorting properties of latin1_german1_ci and utf8_unicode_ci (the sorting shown is done according to the German DIN 5007 standard).