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id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT
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id BIGINT unsigned auto_increment NOT NULL,
to prevent negative values from being inserted.
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An unsigned type can be used to permit only nonnegative numbers in a column
or when you need a larger upper numeric range for the column.
For example, if an INT column is UNSIGNED ,
the size of the column's range is the same
but its endpoints shift up,
from -2147483648 and 2147483647 to 0 and 4294967295 .
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INT stands for interger, so it is interger values.
INT can contain zero, positive and negetive values.
INT cannot contain fraction values, only hole numbers are excepted.