Why can't tinyint store more than the number 255 in MySQL?

If TINYINT can store three characters, for example, why can't it store up to t开发者_JAVA百科he number 999?

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Because it takes only 8 bit and hence can encode no more than 2^8 = 256 values.

The three characters you see in something like '123' are the result of the binary to decimal conversion. You cannot store arbitrary 3 characters there.

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It is 8 bits and can actually store a maximum value of 255. 8 bits have 256 possible states including zero.