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Character Sets and Collations

Character Sets and Collations

A character set is a set of symbols and encodings. A collation is a set of rules for comparing characters in a character set. Let's make the distinction clear with an example of an imaginary character set.
Suppose that we have an alphabet with four letters: 'A', 'B', 'a', 'b'. We give each letter a number: 'A' = 0, 'B' = 1, 'a' = 2, 'b' = 3. The letter 'A' is a symbol, the number 0 is the encoding for 'A', and the combination of all four letters and their encodings is a character set.
Now, suppose that we want to compare two string values, 'A' and 'B'. The simplest way to do this is to look at the encodings: 0 for 'A' and 1 for 'B'.
Because 0 is less than 1, we say 'A' is less than 'B'. Now, what we've just done is apply a collation to our character set.
The collation is a set of rules (only one rule in this case): "compare the encodings." We call this simplest of all possible collations a binary collation.
collation binary-collation character-sets

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