Re: int(10) va int(11)
On Mon, 14 Jun 2010, Michael Dykman wrote: 11 characters of display allow for any int of any size, signed or unsigned. When you do not specify a length attribute in a declaration, MySQL uses 11 as the default. As an astrophysicist, I've always considered a flaw the fact that mysql (or SQL in general ?) mix up things like the number of bytes taken by a quantity, and the number of digits recommended for display. In our parliance (e.g. the FITS data format used by the International Astronomical Union for data exchange) this is mixing up TTYPE (e.g. 8- 16- or 32- bit integers, 32- or 64-bit floats) and TDISP (the Fortran-like format suggested for display). In mysql I always use the generic type (int or float or double, rarely things like bigint or tinyint) for numeric quantities, without any number-of-digit indication. For floats they are not just used for display, but sometime affect also comparison and that's very annoying if you work usually with numbers like 1.43E-12 ! -- Lucio Chiappetti - INAF/IASF - via Bassini 15 - I-20133 Milano (Italy) Citizens entrusted of public functions have the duty to accomplish them with discipline and honour [Art. 54 Constitution of the Italian Republic] For more info : http://www.iasf-milano.inaf.it/~lucio/personal.html -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org
Re: int(10) va int(11)
11 characters of display allow for any int of any size, signed or unsigned. When you do not specify a length attribute in a declaration, MySQL uses 11 as the default. For your application, use what makes sense for your problem's domain. - michael dykman On Mon, Jun 14, 2010 at 12:14 PM, Ryan Chan ryanchan...@gmail.com wrote: Assume MySQL int range (unsigned) is from 0 to 4294967295 There are total 10 digits. Why a lot of tutorial in the web tell you to declare, e.g. CREATE TABLE t1 (f INT(11) UNSIGNED); -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=mdyk...@gmail.com -- - michael dykman - mdyk...@gmail.com May the Source be with you. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org
RE: int(10) va int(11)
AFAIK, the number in parenthesis is ONLY for display purposes in formatting the size of the column in mySQL command line output, NOT the size of the data that can be held. I think they use (11) because unsigned will need one extra character for the minus sign. INT SIGNED = -2147483648 to 2147483647 Now this changes for things like a CHAR(2) where that *IS the column is only going to handle 2 characters. Or VARCHAR(10) where that column will handle from 0 to 10 characters. Same goes for FLOAT(7,4) which means 7 total digits and 4 of them are decimal places. But for *INT columns, I don't think the same is true. It's cosmetic only. Someone PLEASE correct me if I'm wrong. It's kind of silly if you ask me. This one special case just adds confusion. http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html Another extension is supported by MySQL for optionally specifying the display width of integer data types in parentheses following the base keyword for the type (for example, INT(4)). This optional display width may be used by applications to display integer values having a width less than the width specified for the column by left-padding them with spaces. (That is, this width is present in the metadata returned with result sets. Whether it is used or not is up to the application.) The display width does not constrain the range of values that can be stored in the column, nor the number of digits that are displayed for values having a width exceeding that specified for the column. For example, a column specified as SMALLINT(3) has the usual SMALLINT range of -32768 to 32767, and values outside the range allowed by three characters are displayed using more than three characters. -Original Message- From: Ryan Chan [mailto:ryanchan...@gmail.com] Sent: Monday, June 14, 2010 9:14 AM To: MySql Subject: int(10) va int(11) Assume MySQL int range (unsigned) is from 0 to 4294967295 There are total 10 digits. Why a lot of tutorial in the web tell you to declare, e.g. CREATE TABLE t1 (f INT(11) UNSIGNED); -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=dae...@daevid.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org
