pb5中select语句into后接两个变量名是什么意思

Error reporting   Not all DBMSs return a conversion error when the data type of a column does not match the data type of the associated variable.

The following statement uses the indicator variable IndVar2 to see if Address contains a NULL value:



if IndVar2 = -1 then...



You could also use the PowerScript IsNull function to accomplish the same result without using indicator variables:



if IsNull( Address ) then ...



This statement uses the indicator variable IndVar3 to set City to NULL:



IndVar3 = -1 



You could also use the PowerScript SetNull function to accomplish the same result without using indicator variables:



SetNull( City ) 

Using indicator variables 



PowerBuilder supports indicator variables, which are used to identify NULL values or conversion errors after a database retrieval. Indicator variables are integers that are specified in the HostVariableList of a FETCH or SELECT statement.

Each indicator variable is separated from the variable it is indicating by a space (but no comma). For example, this statement is a HostVariableList without indicator variables:



:Name, :Address, :City



The same HostVariableList with indicator variables might look like this:



:Name :IndVar1, :Address :IndVar2, :City :IndVar3



Indicator variables have one of these values:



Numerical value	Meaning

 0	Valid, non-NULL value

-1	NULL value

-2	Conversion error