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
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 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
Get data type:1. If you want to see the value and type of an expression, use Var_dump ().2. If you just want an easy-to-read type of expression for debugging, use GetType ().3. To view a type, do not use GetType () and use the Is_type ()
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
Both cast and convert in SQL Server convert an expression from one data type to another data type. Because SQL Server provides two features, it can be confusing to choose which feature should be chosen or in which case the feature should be used.
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
Document directory
Data Type Conversion
Data Type Conversion
In Transact-SQL, there may be two levels of data type conversion:
When the data of one object is moved to another object, or the data between two objects is compared or combined,
1. The round () function is used in rounding. The first parameter is the data to be operated, and the second parameter is used to display the number of decimal places after rounding.
2.The numeric function has two parameters. The first parameter
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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