You can use variables embedded in function-string input or output templates as symbolic markers for various runtime values.
A variable can represent a column name, the name of a system-defined variable, the name of a parameter in a user-defined function, or a user-defined variable defined in an input template. The variable must refer to a value with the same datatype as anything to which it is assigned.
Function-string variables are enclosed inside of a pair of question marks (?), as shown:
?variable!modifier?
The modifier portion of a variable identifies the type of data the variable represents. The modifier is separated from the variable name with an exclamation (!).
The rs_truncate function string accepts position-based function string variable in the format:
?n!param?
Where n is a number from 1 to 255, representing the position of function parameter in the LTL. The first parameter for rs_truncate in the LTL is represented in function string as ?1!param?. For position based function string variable, the only acceptable modifier is param.
A sample function string for rs_truncate with the position-based variable is as follows:
truncate table publishers partition ?1!param?