Original: http://www.2cto.com/database/201310/250880.htmlSQL cast and CONVERT usage detailed Summary: The following applies only to Mysqlselect {fn CONCAT (CONVERT (User_id,char), user_name)} as Str from T_SYS_ User following this applies only to
An error occurs during compilation:
Error: cast from 'Char * 'to 'int' loses precision
Cause: the program exists.
Char * addrCom; addrCom =... // assign the value if (-1 = (int) addrCom) // causes a compilation error {......}
The above is
This article refers to "in-depth understanding of computer systems" P31.First look at the following code: 12345 hexadecimal representation: 0x000030391#include 2 3 intMain ()4 {5 intA =12345;6 Char*q = (Char*) (&a);7 for(inti =0; I
Town Field Poem:——— Dream who feel, the water month Build blog. Baiqian tribulation, only know the vicissitudes of the world.——— today holds the Buddhist language, the technology is boundless willing to learn. Willing to do what you learn, cast a
Binary negative Number:The original code is the original representation methodAnti-code is the inverse of the sign bit (highest bit)Complement = anti-code +1 1 bytes It can only represent 256 numbers anyway, because there is a sign, so we're going
In mysql, if I use common data sorting methods, we may not get the expected results, but mysql provides us with the CAST CONVERT function, which can CONVERT numbers accordingly, I used this function to sort Chinese characters in the past.
Let's
Simple to say about MySQL's varchar sorting problem, a cautionary tale.
Sample Table structure:
Let's take a look at my table structure
code is as follows
copy code
Show create table Cardserver G **************
Reprint Address: http://hi.baidu.com/thewillreigns/blog/item/67e665c4296e69c038db492d.html
Char and unsigned char are unsignedBoth are used words as words that are indistinguishable, but when integers are used differently:Char integer range is-128
MySQL provides us with two types of conversion functions: cast and convert, how can we let go of the ready-made stuff?1 BINARY[(N)]2 CHAR[(N)]3 DATE4 DATETIME5 DECIMAL6Signed[INTEGER]7 Time8UNSIGNED[INTEGER]Example:--use cast to convert varchar to
Replace, concat, and cast character string functions in mysql need to export a personal information of job-seeking users. This information requires three-table joint query requirements: birthdate format: 1990.01.02 Database: Gender display: men and
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.