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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 theSUBSTRINGfunction 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 SUBSTRING function 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>(&apos;Hello, World&apos;,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

New formula

Parameter: Formula type

Single row formula

Parameter: Formula

substring(ZipCode,1,3)

Transformation Name

New formula

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