%PLUS converts numbers or numeric strings to canonical form, then returns these expression values in numeric collation sequence.
A number can contain leading and trailing zeros, multiple leading plus and minus signs, a single decimal point indicator (.), and the E exponent indicator. In canonical form, all arithmetic operations are performed, exponents are expanded, signs are resolved to either a single leading minus sign or no sign, and leading and trailing zeros are stripped.
A numeric literal can be specified with or without enclosing string delimiters. If a string contains non-numeric characters, %PLUS truncates the number at the first non-numeric character, and returns the numeric part in canonical form. A non-numeric string (any string that begins with a non-numeric character) is returned as 0. %PLUS also returns NULLs as 0.
%PLUS is an InterSystems SQL extension and is intended for SQL lookup queries.
You can perform the same collation conversion in ObjectScript using the Collation()Opens in a new tab method of the %SYSTEM.UtilOpens in a new tab class:
Compare %PLUS to %MVR collation, which sorts a string based on the numeric substrings within the string.
The following examples uses %PLUS to return Home_Street addresses in numeric order:
ORDER BY %PLUS(Home_Street)
Note that the above example orders the integer part of the street address in ascending numerical order. Compare this with the following ORDER BY example, which orders records by street addresses in collation sequence:
ORDER BY Home_Street