SUBSTRING Function

Matches some or all of a string, based on the user-defined starting and ending index values within the string.
  • Input can be a column reference or a string literal value.
  • Since the SUBSTRING function matches based on fixed numeric values, changes to the length or structure of a data field can cause your recipe to 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 the extract transform instead. See Extract Transform.

Basic Usage

Column reference example:

derive type:single value:SUBSTRING(MyName,0,5)

Output: The first five letters of the MyName column value is written to the new column.

String literal example:

derive type:single value:SUBSTRING('Hello, World',0,5)

Output: The string Hello is written to the new column.

Syntax

derive type:single value:SUBSTRING(column_string,start_index,end_index)

ArgumentRequired?Data TypeDescription
column_stringYstringName of the column or string literal to be applied to the function
start_indexYinteger (non-negative)Index value for the start character from the source column or value
end_indexYinteger (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.

column_string

Name of the column or string constant to be searched.

  • Missing string or column values generate missing string results.
  • String constants must be quoted ('Hello, World').
  • Multiple columns and wildcards are not supported.

Usage Notes:

Data TypeRequired?Example Value
StringYesMyName

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 TypeRequired?Example Value
Integer (non-negative)Yes0

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 TypeRequired?Example Value
Integer (non-negative)Yes5

Examples

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:

LastNameZipCode
Able94101
Baker23502-1122
Charlie36845

Transform:

You are interested in the region and area or town identifiers within a zip code region. You can use the following transforms applied to the ZipCode column to extract this information:

derive type:single value:SUBSTRING(ZipCode,1,3)

derive type:single value: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 transform, too. If the data is limited to five-digit zip codes, you could use the RIGHT function.

Results:

LastNameZipCodesubstring_ZipCodesubstring_ZipCode2
Able941014101
Baker23502-11223502
Charlie368456845

Was this page helpful? Let us know how we did:

Send feedback about...

Google Cloud Dataprep Documentation