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
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
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 **************
The MYSQL Cast function is a very important MYSQL function. The following describes the syntax and usage of the MYSQL Cast function in detail, hoping that you can have a better understanding of the MYSQL Cast function.
BINARYThe BINARY operator
Charvarcharvarchar2 differences: 1. the length of CHAR is fixed, while the length of VARCHAR2 can be changed. For example, the storage string "abc", for CHAR (20 ), it indicates that the characters you store will occupy 20 bytes (including 17 null
Char varchar varchar2 the difference http://blog.csdn.net/honglei_zh/article/details/7172538Difference:1. The length of the char is fixed, and the length of the VARCHAR2 is changeable, for example, storing the string "abc", for Char (20), which
GrammarUse CAST:
CAST (expression as data_type)
Use CONVERT:
CONVERT (data_type[(length)], expression [, style])
ParametersExpression
Is any valid Microsoft SQL Server expression. For more information, see expressions.
Data_type
The data
SyntaxUse CAST:
CAST (expression AS data_type)
Use CONVERT:
CONVERT (data_type [(length)], expression [, style])
ParametersExpression
Is any valid Microsoft SQL Server "expression. For more information, see expressions.
Data_type
The data types
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