Sybase Convert函数

CONVERT function [Data type conversion]

Returns an expression converted to a supplied data type.

Syntax

CONVERT( datatype, expression [ , format-style ] )

Parameters

• datatype

  The data type to convert the expression into. Set the data type explicitly, or specify the %TYPE attribute to set the data type to the data type of a column in a table or view, or to the data type of a variable.

• expression

  The expression to be converted.

• format-style

  The style code to apply to the output value. Use this parameter when converting strings to date or time data types, and vice versa. The table below shows the supported style codes, followed by a representation of the output format produced by that style code. The style codes are separated into two columns, depending on whether the century is included in the output format (for example, 06 versus 2006).

  Style code 0 is used if an argument is not provided.

  Without century (yy) style codesWith century (yyyy) style codesOutput format-0 or 100Mmm dd yyyy hh:nnAA1101mm/dd/yy[yy]2102[yy]yy.mm.dd3103dd/mm/yy[yy]4104dd.mm.yy[yy]5105dd-mm-yy[yy]6106dd Mmm yy[yy]7107Mmm dd, yy[yy]8108hh:nn:ss-9 or 109Mmm dd yyyy hh:nn:ss:sssAA10110mm-dd-yy[yy]11111[yy]yy/mm/dd12112[yy]yymmdd-13 or 113dd Mmm yyyy hh:nn:ss:sss (24 hour clock, Europe default + milliseconds, 4-digit year )-14 or 114hh:nn:ss:sss (24 hour clock)-20 or 120yyyy-mm-dd hh:nn:ss (24-hour clock, ODBC canonical, 4-digit year)-21 or 121yyyy-mm-dd hh:nn:ss.sss (24 hour clock, ODBC canonical with milliseconds, 4-digit year )

Returns

Depends on the data type specified.

Remarks

The CONVERT function can be used to convert a string to a DATE, TIME, or TIMESTAMP data type, provided that there is no ambiguity when parsing the string. If format-style is specified, then the database server may use it as a hint on how to parse the string. The database server returns an error if it cannot parse the string unambiguously.

UltraLite: This function is similar to the CAST function but allows you to specify a format style to assist with date and time data type conversions.

Standards

• ANSI/ISO SQL Standard

  The CONVERT function is defined in the ANSI/ISO SQL Standard. However, in the Standard the purpose of CONVERT is to perform a transcoding of the input string expression to a different character set, which is implemented in the software as the CSCONVERT function.

Example

The following statements illustrate the use of format style:

SELECT CONVERT( CHAR( 20 ), OrderDate, 104 ) FROM GROUPO.SalesOrders;

OrderDate16.03.200020.03.200023.03.200025.03.2000...

SELECT CONVERT( CHAR( 20 ), OrderDate, 7 ) FROM GROUPO.SalesOrders;

OrderDateMar 16, 00Mar 20, 00Mar 23, 00Mar 25, 00...

The following statement illustrates conversion to an integer and returns the value 5:

SELECT CONVERT( integer, 5.2 );

The following statement converts a value to the data type defined for the BirthDate column (DATE data type) of the Employees table:

SELECT CONVERT ( Employees.BirthDate%TYPE, '1966-10-30' );