Type conversions can happen automatically, or they can be explicitly requested using the CAST or CONVERT function. The following functions can also be used to force type conversions:
DATE function Converts the expression into a DATE, and removes any hours, minutes or seconds. Conversion errors can be reported.
DATETIME function Converts the expression into a TIMESTAMP, and removes any time zone. Conversion errors can be reported.
STRING function This function is equivalent to CAST(value AS LONG VARCHAR).
VALUE+0.0 Equivalent to CAST( value AS DECIMAL ).
The following list is a high-level view of automatic data type conversions:
If a string is used in a numeric expression or as an argument to a function that expects a numeric argument, the string is converted to a number.
If a number is used in a string expression or as a string function argument, it is converted to a string before being used.
All date constants are specified as strings. The string is automatically converted to a date before use.
There are certain cases where the automatic database conversions are not appropriate. For example, the automatic data type conversion fails in the example below.
'12/31/90' + 5 'a' > 0
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2013, SAP AG ou société affiliée SAP - SAP Sybase SQL Anywhere 16.0|