Is there a difference in using INT(1) vs TINYINT(1) in MySQL?

问题

I'm under the assumption that INT(1) is the exact same thing as TINYINT(1) but I really have no idea. Whenever I've had values that can only be a single integer (e.g. a value 0-9), I've always just used INT(1) to say it's an integer and it will only be one character, which I assume means that it could only be a value 0 through 9 (please explain this to me if I'm wrong). I've always just ignored the other types of INT that you can cast the number as. I'm no MySQL savvy and tend to avoid the more complicated things you can do with it.

So my question, is there any difference between the various integer types INT, TINYINT, SMALLINT, MEDIUMINT, and BIGINT if you define a length of 1 for each type;? If not, should I use them anyways (I can see using them for more semantic meaning, TINYINT being more specific than just INT)? If so, could I easily (and/or should I) just go through my database and change all my INT(1) fields to TINYINT(1) fields?

回答1:

The number in parentheses for integer column types is the "display width". This does not effect the storage requirements as they are pre-defined.

回答2:

Here you'll understand it in a better way!

tinyint: 1 byte, -128 to +127 / 0 to 255 (unsigned)
smallint: 2 bytes, -32,768 to +32,767 / 0 to 65,535 (unsigned)
mediumint: 3 bytes, -8,388,608 to 8,388,607 / 0 to 16,777,215 (unsigned)
int/integer: 4 bytes, -2,147,483,648 to +2,147,483,647 / 0 to 4,294,967,295 (unsigned)
bigint: 8 bytes, -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 / 0 to 18,446,744,073,709,551,615 (unsigned)

回答3:

As the accepted answer explained :

The number in parentheses indicates the number of characters to display that field, not the storage size of the field.

But if you want to know the storage size, you should check the MySQL source documents.

Source: MySQL Docs: Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT

TINYINT : 1 byte, -128 to 127 signed, 0 to 255 unsigned

SMALLINT : 2 bytes, -32768 to 32767 signed, 0 to 65535 unsigned

MEDIUMINT : 3 bytes, -8388608 to 8388607 signed, 0 to 16777215 unsigned

INT : 4 bytes, -2147483648 to 2147483647 signed, 0 to 4294967295 unsigned

BIGINT : 8 bytes, -2^63 to 2^63-1 signed, 0 to 2^64-1 unsigned

来源：https://stackoverflow.com/questions/8045327/is-there-a-difference-in-using-int1-vs-tinyint1-in-mysql

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mysql

types

integer