SUBSTRING Function
Matches some or all of a string, based on the user-defined starting and ending index values within the string.
Input must be a string literal value.
Since the
SUBSTRINGfunction matches based on fixed numeric values, changes to the length or structure of a data field can cause your recipeto fail to properly execute.The
SUBSTRINGfunction requires numerical values for the starting and ending values. If you need to match strings using patterns, you should use theextracttransform instead. SeeExtract Transform.
Wrangle vs. SQL: This function is part of Wrangle, a proprietary data transformation language. Wrangle is not SQL. For more information, see Wrangle Language.
Basic Usage
<span>substring</span><span>('Hello, World',0,5)</span>
Output: Returns the string: Hello.
Syntax and Arguments
substring(string_val,start_index,end_index)
Argument | Required? | Data Type | Description |
|---|---|---|---|
string_val | Y | string | String literal to be applied to the function |
start_index | Y | integer (non-negative) | Index value for the start character from the source column or value |
end_index | Y | integer (non-negative) | Index value for the end character from the source column or value |
For more information on syntax standards, see Language Documentation Syntax Notes.
string_val
String constant to be searched.
Missing string values generate missing string results.
String constants must be quoted (
'Hello, World').Multiple columns and wildcards are not supported.
Usage Notes:
Data Type | Required? | Example Value |
|---|---|---|
String | Yes | 'This is my string.' |
start_index
Index value of the character in the string to begin the substring match.
The index of the first character of the string is
0.Value must be less than
end_index.If this value is greater than the length of the string, a missing value is returned.
Usage Notes:
Data Type | Required? | Example Value |
|---|---|---|
Integer (non-negative) | Yes | 0 |
end_index
Index value of the character in the string that is one after the end the substring match.
Value must be greater than
start_index.If this value is greater than the length of the string, the end of the string is the end of match. If you know the maximum length of your data, you can use that value here.
Usage Notes:
Data Type | Required? | Example Value |
|---|---|---|
Integer (non-negative) | Yes | 5 |
Examples
Suggerimento
For additional examples, see Common Tasks.
Example - Sectional Information in Zipcodes
Source:
A US zip code contains five digits with an optional Zip+4 extension consisting of four digits. Valid zip code values can be a mixture of these formats.
Within zip code values, each digit has significance:
Digit 1: Zip code section
Digits 2-3: Region within section
Digits 4-5: area or town within region
Digits 6-9: Optional Zip+4 identifier within area or town
Here is some example data:
LastName | ZipCode |
|---|---|
Able | 94101 |
Baker | 23502-1122 |
Charlie | 36845 |
Transformation:
You are interested in the region and area or town identifiers within a zip code region. You can use the following transformations applied to the ZipCode column to extract this information:
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | substring(ZipCode,1,3) |
Transformation Name | |
|---|---|
Parameter: Formula type | Single row formula |
Parameter: Formula | substring(ZipCode,3,5) |
Since the string can be five or ten characters in length, you need to use the SUBSTRING function in the second transformation, too. If the data is limited to five-digit zip codes, you could use the RIGHT function.
Results:
LastName | ZipCode | substring_ZipCode | substring_ZipCode2 |
|---|---|---|---|
Able | 94101 | 41 | 01 |
Baker | 23502-1122 | 35 | 02 |
Charlie | 36845 | 68 | 45 |