I am using MySQL and InnoDB.
I need to store a numeric id which length can vary but needs to be at least 10. For instance:
0000000001
11111111111 are both correct values.
Currently, I my column has the following attributes: bigint(10), unsigned zerofill. This works: if I try to insert "1" then "0000000001" is actually inserted, and if I insert a bigger number (with length>10) it also works.
So, in the end, what is the purpose of the length attribute in the field definition? I thought it was the maximum length, but apparently it is not the case...? Or is my current implementation going to crash eventually?
The length attribute is just a hint for MySQL how to format select query results in the command line client. Nothing more. It has no effect on the datatype actually. An int is an int with 4 bytes, no matter what length you specify. Same of course for bigint, but with 8 bytes.
Related
I made a table for storing contact record of user of my website. It also contains a 10 digit mobile no.
Table structure is like this:
CREATE TABLE contact_user
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
contact INT(10)
)
Now the problem is that if I insert a 10 mobile no.(e.g.9595891256) using phpmyadmin into contact field it will insert some random value and shows a warning saying "data out of column range"
But if I insert a simple 10 digit no (e.g.4561327894) then it works well and no warning is shown.
SO please tell me what is the issue in inserting a mobile no in this column?
I am using mysql 5.1 on ubuntu 11.04 and also using phpmyadmin.
INT(10) does not mean a 10-digit number, it means an integer with a display width of 10 digits. Whether you put INT(2) or INT(10), MySQL still only stores an (unsigned, in this case) INT which has a maximum value of 4294967295.
You can use a BIGINT instead of INT to store it as a numeric. I wouldn't recommend this, however, because it won't allow for international numbers. If you are certain your application will only use US numbers, using BIGINT will save you 3 bytes per row over VARCHAR(10) -- if that sort of thing concerns you.
Since it is a phone number (and therefore you won't be doing numeric calculations against it), try using a VARCHAR(20). This allows you the ability to store international phone numbers properly, should that need arise.
The maximum value for an INT in MySQL is 2147483647 (or 4294967295 if unsigned), according to the MySQL documentation. If your value exceeds this limit, you integer will overflow, hence the not-that-random value.
Also, INT is not the best solution to store phone numbers. You might lose leading zeros if they are one or more. Also, international phone numbers start with a + sign. Consider using a VARCHAR. This will end up using more space in the database, but will provide more consistency.
It is because of the max size of type INT you need to use a different type to hold a number that large. Try using BIGINT.
I'm using phpMyAdmin to create my table structures.
I can read from the documentation pages on MySQL about size limits for Integer Types:
MySQL Integer Types Reference
So here is where I'm getting a little confused with creating a column.
I want to create a column in the table: tbl_note_categories called notescounter
I don't foresee myself creating thousands of noteids in the tbl_notes with any specific categoryid. But I do believe I'd create hundreds of notes to each categoryid.
I'm at that point of choosing between: tinyint, smallint, mediumint.
According the documentation link above, I'm guessing smallint is my best choice.
So here's my confusion. PhpMyAdmin asks for a Length/Values parameter to be specified.
I'm going to make sure this new column (notescounter) is unsigned, giving me up to 65536.
Does that mean I need the Length/Values to be (5)?
I'm guessing Length is character length, but I'm not sure. (comparing to varchar)
No, this is a common misconception about MySQL. In fact, the "length" has no effect on the size of an integer or the range of values it can store.
TINYINT is always 8 bits and can store 28 distinct values.
SMALLINT is always 16 bits and can store 216 distinct values.
INT is always 32 bits and can store 232 distinct values.
BIGINT is always 64 bits and can store 264 distinct values.
There's also a MEDIUMINT, but the engineers who work on MySQL tell me MEDIUMINT always gets promoted to a 32-bit INT internally, so there's actually no benefit to using MEDIUMINT.
The length is only for display, and this only matters if you use the ZEROFILL option.
See an example in my answer to What is the difference (when being applied to my code) between INT(10) and INT(12)?
Yes, you want to specify a length of 5.
In MySQL, the "length" attribute on the integer types is optional. It's a MySQL extension which is non-standard).
When it is omitted from the column declaration, MySQL provides a default value. For a SMALLINT UNSIGNED, the default value is 5.
This value does NOT have any impact on the range of values that can be stored for an integer type. It specifies a "display length", which is returned in resultset metadata, which a client can choose to use or ignore.
http://dev.mysql.com/doc/refman/5.5/en/numeric-type-attributes.html
I made a table for storing contact record of user of my website. It also contains a 10 digit mobile no.
Table structure is like this:
CREATE TABLE contact_user
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
contact INT(10)
)
Now the problem is that if I insert a 10 mobile no.(e.g.9595891256) using phpmyadmin into contact field it will insert some random value and shows a warning saying "data out of column range"
But if I insert a simple 10 digit no (e.g.4561327894) then it works well and no warning is shown.
SO please tell me what is the issue in inserting a mobile no in this column?
I am using mysql 5.1 on ubuntu 11.04 and also using phpmyadmin.
INT(10) does not mean a 10-digit number, it means an integer with a display width of 10 digits. Whether you put INT(2) or INT(10), MySQL still only stores an (unsigned, in this case) INT which has a maximum value of 4294967295.
You can use a BIGINT instead of INT to store it as a numeric. I wouldn't recommend this, however, because it won't allow for international numbers. If you are certain your application will only use US numbers, using BIGINT will save you 3 bytes per row over VARCHAR(10) -- if that sort of thing concerns you.
Since it is a phone number (and therefore you won't be doing numeric calculations against it), try using a VARCHAR(20). This allows you the ability to store international phone numbers properly, should that need arise.
The maximum value for an INT in MySQL is 2147483647 (or 4294967295 if unsigned), according to the MySQL documentation. If your value exceeds this limit, you integer will overflow, hence the not-that-random value.
Also, INT is not the best solution to store phone numbers. You might lose leading zeros if they are one or more. Also, international phone numbers start with a + sign. Consider using a VARCHAR. This will end up using more space in the database, but will provide more consistency.
It is because of the max size of type INT you need to use a different type to hold a number that large. Try using BIGINT.
I created a table with column id as int data type. However, I realized that int type may not be able to hold some of the values I might put in the table. I wish to find out, if I define the column as bigint, does it take up "space" or does it use space on the database EVEN before I put a value in the column? I am using sql server 2008 R2. Thank you.
int always uses 4 bytes, bigint always uses 8 bytes. The actual value stored does not affect the size of the field.
Every time you enter any number, even 1, it will use the full 8 bytes. So the extra storage overhead is 4bytes * number of rows. If you are worried that you numbers will grow higher than 2,147,483,647, then you should use bigint.
Im new to Database programming and I have a very basic question:
In my PHPMyAdmin GUI that Im using to create tables in my database, what does it mean when the column "type" (ie. datatype) has the data type and something in brackets after that.
For example:
int(20), bigint(30) .....
I understand the type int and bigint imply the number of bytes that are used and consequently the range of values that can be stored. But what does the value in the brackets mean?
What does the (20) and the (30) stand for.... what impact does this have on....
Sorry if the Q is basic, I am trying to understand databases....
Thanks a lot
Basically this is a Display Width.
I've found very good explanation of this concept here is so decided to not describe it myself and let you read it yourself from the original source.
In the same way that a max-length can be specified for string data types (e.g. VARCHAR(5) = Maximum 5 Characters), Numeric data type cells can have a "Display Length" specified ( E.g.: INT(5) ).
There is a common misconception that specifying a Display Length on an INT column will limit that column's range. As example, it is quite often thought that defining a column as INT(1) will reduce the column's unsigned range to 0 - 9, and that INT(2) would reduce the column's unsigned range to 0 - 99. This is not the case. An INT data column will ALWAYS have a viable unsigned range of 0 - 4294967295, or a signed range of -2147483648 to 2147483647, irrespective of the specified Display Width, whether it be 1 ( INT(1) ) or 20 ( INT(20) ).
Display width doesn't change storage requirements for a data type.
Display width doesn't alter the actual data in any way (ie: it stores the entire value for the data)
A column returns it's full value when called in a query, regardless of the display width (the book directly contradicts this claim it makes as seen above)
The value in the bracket is the size or length of the field. [Edit strike]If set to 2 a uint field can only host values from 0 to 99.[/strike] You can set this value on your own and thus save a bit of memory if you expect your values not to exceed this limitation. Useful in connection with varchar.
Here another thread about varchar sizes: What are the optimum varchar sizes for MySQL?
Link to the mysql doc which explains it http://dev.mysql.com/doc/refman/5.7/en/numeric-type-attributes.html