How do I represent this data in mysql?
16 bit unsigned integer -----Range: 0x0000 - 0xFFF7
64 bit unsigned int. Depicted as xx:xx:xx:xx:xx:xx:xx:xx -----Range: 0x0000 - 0xFFFFFFFFFFFFFFFF
2 bits ----- 00 - None, 01 - Residential Security, 10 - High Security
32 bit unsigned int
Should I convert everything to string and convert it at application layer?
According to MySQL's Overview of Numeric Types:
UNSIGNED SMALLINT: range is 0 to 65535. This would be sufficient for 16-bit unsigned ints.
UNSIGNED TINYINT: range is 0 to 255. Sufficient for 2-bit unsigned int. It appears you would need to preserve leading zeroes, so use ZEROFILL too. To keep the value to just two characters wide, you can specify UNSIGNED ZEROFILL TINYINT(2).
UNSIGNED INT: range is 0 to 4294967295. Sufficient for 32-bit unsigned int.
UNSIGNED BIGINT: range is 0 to 18446744073709551615. See below:
The last one, the 64-bit unsigned int, has a couple of caveats, from the above linked page:
All arithmetic is done using signed BIGINT or DOUBLE values, so you should not use unsigned big integers larger than 9223372036854775807 (63 bits) except with bit functions! If you do that, some of the last digits in the result may be wrong because of rounding errors when converting a BIGINT value to a DOUBLE.
You can always store an exact integer value in a BIGINT column by storing it using a string. In this case, MySQL performs a string-to-number conversion that involves no intermediate double-precision representation.
The -, +, and * operators use BIGINT arithmetic when both operands are integer values. This means that if you multiply two big integers (or results from functions that return integers), you may get unexpected results when the result is larger than 9223372036854775807.
MySQL support several data types. See MySQL Data Types
UNSIGNED BIGINT : 8-byte (64-bit) integer
UNSIGNED INT : 4-byte (32-bit) integer
UNSIGNED SMALLINT : 2-byte (16-bit) integer
For the 2-bit type, you may use the TINYINT (8-bit) or the ENUM datatype.
Related
I am using a column to store UNIX timestamp in seconds (divide it by 1000). I found bigint datatype to be large enough to store it. I created it using
...
createTimeStamp bigint,
...
However, when I ran
show create table tablename
It had created it as bigint(20). I did not notice it until my sort started running into problems. I then modified the schema to make it bigint(8) expressly as in:
alter table tablename modify createTimeStamp bigint(8)
and the sort functions well.
I researched and realized that bigint(20) has nothing to do with storage and is only used for display by padding spaces. If so, why is the sort not functioning when using bigint(20)?
Mysql alludes to errors when using numbers that exceed 64 bits.
http://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html
BIGINT[(M)] [UNSIGNED] [ZEROFILL]
A large integer. The signed range is -9223372036854775808 to
9223372036854775807. The unsigned range is 0 to 18446744073709551615.
...
...
Some things you should be aware of with respect to BIGINT columns:
All arithmetic is done using signed BIGINT or DOUBLE values, so you
should not use unsigned big integers larger than
9223372036854775807 (63 bits) except with bit functions! If you do
that, some of the last digits in the result may be wrong because of
rounding errors when converting a BIGINT value to a DOUBLE.
I've created field named e2s with tinyint datatype. When I store the value of 500 it converts it into 127. Now I changed it to smallint. It stored value 500. Why?
What is the difference between int, tinyint, smallint, mediumint, bigint to store values.
Take a look at http://dev.mysql.com/doc/refman/5.0/en/integer-types.html. TINYINT only stores 1 byte of data, thus allowing the integer range of storage from -128 to 127.
SMALLINT in other hand uses 2 bytes of storage, having a much wider range from -32768 to 32767.
Be aware of what you are going to store in TINYINT or SMALLINT columns. For instance, it's a bad idea to set an auto_increment PK column to SMALLINT datatype as you could easily overwhelm it's capacity.
Please see MySql reference on integer types:
http://dev.mysql.com/doc/refman/5.1/en/integer-types.html
It shows you the minimum and maximum values you can store.
I read the answers given here: What is the difference between tinyint, smallint, mediumint, bigint and int in MySQL? , so I now know how they store the data, but I'm still not sure how to set my database up. For example, if I want a field to be either 0 or 1 (sort of binary, 0 = off, 1 = on), do I use TINYINT with a length of 1?
My main question is, what does the LENGTH setting determine? As each NUMERIC data type already has their own associated data size.
Also, what is the difference between SIGNED and UNSIGNED, and why should I choose one over the other?
http://dev.mysql.com/doc/refman/5.0/en/numeric-type-overview.html
Diffrence between SIGNED and UNSIGNED is with UNSIGNED you can store only positive numbers.
For example :
about INT (Normal INTEGER) values
The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295.
If you are using PK auto_increment value then you should use UNSIGNED in this case.
http://dev.mysql.com/doc/refman/5.0/en/integer-types.html
This shows storage and range for each INTEGER types.
For binary fields use BIT.
the length of numerics specifies the precision before and after the comma. See here
An integer variable has 32 bits to store the integer value.
In signed integer the first bit is reserved to store positive or negative sign. So, a signed integer can use only 31 bits to store a value and hence its range will be −2,147,483,648 to +2,147,483,647.
Suppose if your program needs to store only positive integer greater than +2,147,483,647. You need to consider the long integer that will take 8 bits that will cause the wastage of memory.
Instead you can go with unsigned integer. In an unsigned integer no bit is reserved for the sign so now you have 32 bits to store the value. The only limitation with an unsigned integer is that you cannot use it to store negative values. The range of an unsigned integer of 32 bits will be 0 to 4,294,967,295.
Hope it clears your concept of signed and unsigned integer.
I have a table in MYSQL in with a primary key id int(11) (auto-incremented). Now I have a program which reads some text file and enters the value in id column.
So my table should contains :
id
897413
791783
But what happens is that, I can't find big numbers in my table. Is this because of maximum value that int(11) can hold? Increased int(11) to int(20) still facing same problem. I can't change the datatype to big int as I have already implemented a lot of code.
EDIT:
I tried to insert a single record with id as 523826 and it got saved in DB as 450258. Why so?
Definition from mysql manual for the int data type:
A normal-size integer. The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295.
The int type is always 4 bytes (32 bits). The 11 in int(11) is just the "display width", that only matters for UNSIGNED ZEROFILL columns. More details on this blog post.
INT in MySQL is 32 bits. INT(11) likely means you have a signed INT, which for an ID is useless. Changing it to an unsigned INT will automatically double the number of IDs available (since nobody uses a negative ID). Even though 11 "seems" bigger, it's because it takes into consideration the "length" of the number if it's the maximum negative number (-2147483648) which is 11 characters long.
BIGINT will let you go up to 64 bits, signed or unsigned. Again, unsigned will allow you twice as many IDs (>0).
As Andrew mentioned above, if your PHP does not support 64 bit integers then you will not be able to easily use them.
Hope that helps.
What's the difference in int(11) and int(11) UNSIGNED ?
An UNSIGNED type cannot be negative, but on the other hand it has twice as large a range for the positive integers. The types TINYINT, SMALLINT, MEDIUMINT,
INT and BIGINT all have signed and unsigned versions.
For INT the ranges are defined as follows:
Type Storage Min Max
INT 4 -2147483648 2147483647
INT UNSIGNED 4 0 4294967295
The signed and unsigned types take the same storage space (4 bytes for INT).
See the documentation for more details.
INT goes from -2147483648 to +2147483647
UNSIGNED INT goes from 0 to 4294967295
the 11 between the braces has no effect on the number, just how it's displayed.
UNSIGNED means that it can hold only nonnegative values, i.e. it can't hold for example -20
UNSIGNED is exactly that, its all positive (no sign) numbers. The size of bytes is the same, but if your data is never negative you can get larger positive numbers out of it. The 11 is the default of how many characters it will fetch and display. For the exact size, do a search for the DBMS you are using and the type.
All integer types can have an optional (nonstandard) attribute UNSIGNED. 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 from -2147483648 and 2147483647 up to 0 and 4294967295.
see here: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html
The unsigned one can't hold negative numbers.
An unsigned integer can handle values from 0 to 2^(size in bits of the integer field). A signed integer can handle values from -2^(size of the integer field-1) to 2^(size of the integer field-1)-1.
I think you may want to know the difference between int and int(10).
Let's give an example for int(10) one with zerofill keyword, one not, the table likes that:
create table tb_test_int_type(
int_10 int(10),
int_10_with_zf int(10) zerofill,
unit int unsigned
);
Let's insert some data:
insert into tb_test_int_type(int_10, int_10_with_zf, unit)
values (123456, 123456,3147483647), (123456, 4294967291,3147483647)
;
Then
select * from tb_test_int_type;
# int_10, int_10_with_zf, unit
'123456', '0000123456', '3147483647'
'123456', '4294967291', '3147483647'
We can see that
with keyword zerofill, num less than 10 will fill 0, but without zerofill it won't
Secondly with keyword zerofill, int_10_with_zf becomes unsigned int type, if you insert a minus you will get error Out of range value for column...... But you can insert minus to int_10. Also if you insert 4294967291 to int_10 you will get error Out of range value for column.....
Conclusion:
int(X) without keyword zerofill, is equal to int range -2147483648~2147483647
int(X) with keyword zerofill, the field is equal to unsigned int range 0~4294967295, if num's length is less than X it will fill 0 to the left