Unlike other types of data, text data has very few restrictions on the kinds of values that appear in a cell. In the application, this data is typically inferred as String data type. As a result, finding string values that mean the same thing can be a challenge, as minor differences in their content or structure can invalidate a match.
This section provides some methods for comparing strings.
- Some target systems may impose limits on the lengths of imported values. For more information on managing the lengths of your strings, see Manage String Lengths.
You can use the following functions to locate sub-strings that are part of a column's value.
The following transformation checks the left five values of the lowercase version of the ProdId column to see if it matches
xxxx-. If the value is detected, then the
ProdName value is set to
Compare String Ends by Pattern
You can use the
ENDSWITH functions to determine if a string begins or ends with a specified pattern.
Tip: These functions are most useful for performing pattern-based checks on strings. For string literals, you can use the
The following transformation inserts the value
error in the
custCodeStatus column if the
custCode value begins with six digits in a row:
See STARTSWITH Function.
See ENDSWITH Function.
You can use the
EXACT function to compare if two strings are exact matches. String inputs can be literals, column references, or expressions that evaluate to strings.
You can nest function expressions inside of the
EXACT reference to eliminate common and perhaps not useful differences between strings. In the following transformation, a value of
true is inserted into the
matches column, if
colB are exact matches, after whitespace and case differences have been removed:
The platform also supports the doublemetaphone algorithm for fuzzy matching. This algorithm provides mechanism for proximity matching; the
DOUBLEMETAPHONEEQUALS function supports an optional second parameter to define the strength of the algorithm.
This algorithm works by generating two separate encodings for each string: a primary encoding and a secondary encoding. You can experiment with these encodings using the
DOUBLEMETAPHONE function. See DOUBLEMETAPHONE Function.
This algorithm can be applied to compare two strings, as in the following transformation.
- The first two parameters of the function are the string literals, column references, or functions returning strings to compare.
The third parameter is optional. It determines the level of matching required to return
Match threshold Description
Both primary encodings must match.
At least one primary encoding must match either of the other string's encodings
A primary or secondary encoding from each can match.
- For more information, see DOUBLEMETAPHONEEQUALS Function.
For string values, you can use the string comparison functions to check how strings compare using Latin collation settings.
Tip: Any column can be converted to String data type to use these functions.