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
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
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
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
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 **************
1 overviewThis article focuses on the two functions involved in type conversion in SQL Server: Cast and convert.2 Specific content2.1 CAST(1) Role: An expression that converts an expression of one data type to another data type.(2) Definition:1 CAST
How to Use substring in oracle Database CONVERT (varchar (12), getdate (), 112), substringgetdate
SqlserverI often need to perform some time-type field conversions, but I don't quite remember it. So I collected the following
1,Primary KeyConstraintsThere are five types of constraints in SQL Server, Primary key constraints, Foreign key constraints, Unique constraints, Default constraints, and Check constraints.There is often a combination of one or more columns in a
Is today in the background to find a sort of problem. So, there's no way to change it. Here is a brief look at MySQL varchar sorting problem, warning.
Sample Table structure:Let's take a look at my table structure
The code is as follows
In SQL, the varchar type is converted to int and then sorted, if our database ID is set to varchar type, the order by ID when queried.If the ID of our database is set to the varchar type of the order by ID at the time of the query, we do not want to
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