4 Byte Unsigned Int in SQL Server

4 byte unsigned int in SQL Server?

It doesn't seem so.

Here's an article describing how to create your own rules restricting an int to positive values. But that doesn't grant you positive values above 2^31-1.

http://www.julian-kuiters.id.au/article.php/sqlserver2005-unsigned-integer

A 4-byte Unsigned Int for Sql Server 2008?

IMO, you have the correct answers to storing 2^32 positive values in 4 bytes: either a standard int and you do the math or a binary(4) which, contrary to what you have said, will only consume 4 bytes of space. (Only varbinary will incur an extra 2 bytes of storage). A series of tinyint or smallint columns would be unjustifiably cumbersome IMO.

Of course there is another solution for storing 2^32 positive values but it takes eight bytes: a bigint with a check constraint. Given how cheap storage and memory is today, IMO, this is the simplest and cheapest solution given the programmatic hoops you will have to jump through with the other solutions, however clearly you have a reason for wanting to save the extra 4 bytes on each row.

Why doesn't SQL Server support unsigned datatype?

If I had to guess, I would say that they are trying to avoid a proliferation of types. Generally speaking there isn't anything that an unsigned integer can do that a signed integer can't do. As for the case when you need a number between 2147483648 and 4294967296 you probably should go to an 8 byte integer since the number will also eventually exceed 4294967296.

SQL Server 2008 – Unsigned Integer Data Types

The main (and rather critical) disadvantage is that it seems that the link you provide doesn't actually do what you think it does.

It merely just makes an new integer type that can only be positive, it doesn't provide you with any space saving that would otherwise result from using an unsigned field (which seems to be your main aim). that is to say that the max value of their unsignedSmallint would be the same as the max value for smallint, you would therefore still be wasting those extra Bits (but more so since you can't insert negative values).

That is to say that their unsignedInt would not allow values above 2^31-1.

I understand and appreciate that in 100 million rows the savings from using a int32 vs int64 on a single column is around 380MB. Perhaps the best way for you to do this is to handle this is to offset your stored value after you read it, ideally within a view and only ever read from that view, and then when doing an insert add -2^31 to the value.. But the problem then is that the parsing for int32 occurs before the insert so INSTEAD OF triggers won't work.. (I do not know of any way to make an INSTEAD OF trigger that accepts different types to that of the owning table)

Instead your only option in this regard is to use stored procedures to set the value, you can then either use a view or a stored proc to get the value back:

create table foo
(fooA int)
GO

CREATE VIEW [bar]
AS
SELECT CAST(fooA AS BIGINT) + 2147483647 AS fooA
FROM foo
GO

CREATE PROCEDURE set_foo
    @fooA bigint
AS
BEGIN
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    IF @fooA < 4294967296 AND @fooA >= 0
        INSERT INTO foo VALUES (@fooA - 2147483647)
    --ELSE
        -- throw some message here
END
GO

This can be tested using:

exec set_foo 123
exec set_foo 555
select * FROM bar
select * FROM foo
exec set_foo 0
exec set_foo 2147483648
exec set_foo 4147483648
select * FROM bar
select * FROM foo

You will see the values are returned unsigned, however the returned values are int64 and not unsigned32 so your application will need to treat them as if they were still int64.

If you have a case where you will see significant improvement from doing this (such as almost every column in the table is twice as big as it otherwise needs to be) then the effort above might be warranted, otherwise I would just stay with bigint instead.

Unsigned integer datatype in column-oriented DBMS

I found one answer on the "How to Migrate from SQL Server" (page4) at Infobright.org:

UNSIGNED INTEGERS – Unsigned integers
have historically been selected by
DBAs and database designers to provide
capacity for larger maximum values for
a given integer field than is possible
with a signed integer. Where negative
values do not exist in the data, or
are not allowed, the approach of
selecting unsigned integers allowed
accommodation of larger values while
selecting smaller data types in
traditional row-oriented technologies.
In Infobright’s case, when unneeded
bytes exist for a particular integer
value, they are “squeezed” out by the
inherent compression algorithms. For
this reason, Infobright recommends
selecting the next-larger integer data
type – for example, BIGINT over
INTEGER, or MEDIUMINT over SMALLINT –
such that the maximum column value can
still be accommodated in the chosen
data type. Infobright doesn’t suffer
the wasted space consequences of
“over- typing” one’s columns.

What is the difference between tinyint, smallint, mediumint, bigint and int in MySQL?

They take up different amounts of space and they have different ranges of acceptable values.

Here are the sizes and ranges of values for SQL Server, other RDBMSes have similar documentation:

• MySQL
• Postgres
• Oracle (they just have a NUMBER datatype really)
• DB2

Turns out they all use the same specification (with a few minor exceptions noted below) but support various combinations of those types (Oracle not included because it has just a NUMBER datatype, see the above link):

             | SQL Server    MySQL   Postgres    DB2
---------------------------------------------------
tinyint      |     X           X                
smallint     |     X           X         X        X
mediumint    |                 X
int/integer  |     X           X         X        X 
bigint       |     X           X         X        X

And they support the same value ranges (with one exception below) and all have the same storage requirements:

            | Bytes    Range (signed)                               Range (unsigned)
--------------------------------------------------------------------------------------------
tinyint     | 1 byte   -128 to 127                                  0 to 255
smallint    | 2 bytes  -32768 to 32767                              0 to 65535
mediumint   | 3 bytes  -8388608 to 8388607                          0 to 16777215
int/integer | 4 bytes  -2147483648 to 2147483647                    0 to 4294967295
bigint      | 8 bytes  -9223372036854775808 to 9223372036854775807  0 to 18446744073709551615 

The "unsigned" types are only available in MySQL, and the rest just use the signed ranges, with one notable exception: tinyint in SQL Server is unsigned and has a value range of 0 to 255

TSQL BITWISE NOT

It's not a byte (8-bits), it's probably a 32-bit number.

Whatever the length (16, 32, or 64), it will have leading 0s. In 16-bit this looks like:

0000 0000 1010 1010 becomes 1111 1111 0101 0101 which is -171.

You can do this yourself with windows calculator with programmer mode, decimal, and anything higher than byte selected. Enter 170 and hit NOT and you get -171, and it will show you the bit representations of each.

Another thing to note would be that 1010 1010 is not actually 170, if it is a signed byte. As a signed byte it would be -86. Inverting it in byte mode yields 85, as you expected.

Note also the difference between signed and unsigned bit patterns. The bit length matters, because for signed integers, a number that starts with a 1 is negative, and you get the absolute value of that negative number by inverting the bits and adding one. (see: Two's Complement)

This is why 1010 1010 (as a byte) gives a positive number if you invert it, and why 0000 0000 1010 1010 gives a negative number if you invert it.

For reference, the integral types in SQL Server are:

• tinyint: byte (1 byte) (8 bits) (unsigned)
• smallint: word (2 bytes) (16 bits) (signed)
• int: dword (4 bytes) (32 bits) (signed)
• bigint: qword (8 bytes) (64 bits) (signed)

Note that while I described signed bytes, it looks like SQL Server does not have signed bytes at all, and does not have larger unsigned integer types at all. So if you use tinyint it will always be unsigned, and if you use anything larger, it will always be signed.

When should I use UNSIGNED and SIGNED INT in MySQL?

UNSIGNED only stores positive numbers (or zero). On the other hand, signed can store negative numbers (i.e., may have a negative sign).

Here's a table of the ranges of values each INTEGER type can store:

^{Source: http://dev.mysql.com/doc/refman/5.6/en/integer-types.html}

UNSIGNED ranges from 0 to n, while signed ranges from about -n/2 to n/2.

In this case, you have an AUTO_INCREMENT ID column, so you would not have negatives. Thus, use UNSIGNED. If you do not use UNSIGNED for the AUTO_INCREMENT column, your maximum possible value will be half as high (and the negative half of the value range would go unused).

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