Preface
The Transformation Language
Constants
Operators
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- Built-in Variables
  - SYSDATE
    - Example
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Dates
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  - Aggregate Functions
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- ABORT
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- MAX (Numbers)
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- NPER
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- PERCENTILE
- PMT
- POWER
- PV
- RAND
- RATE
- REG_EXTRACT
- REG_MATCH
- REG_REPLACE
- REPLACECHR
- REPLACESTR
- RESPEC
- REVERSE
- ROUND (Dates)
- ROUND (Numbers)
- RPAD
- RTRIM
- SET_DATE_PART
- SIGN
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- SIZE
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- SQL_LIKE
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- SUBSTR
- SUM
- SYSTIMESTAMP
- TAN
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- TIME_RANGE
- TO_BIGINT
- TO_CHAR (Dates)
- TO_CHAR (Numbers)
- TO_DATE
- TO_DECIMAL
- TO_DECIMAL38
- TO_FLOAT
- TO_INTEGER
- TO_TIMESTAMP_TZ
- TRUNC (Dates)
- TRUNC (Numbers)
- UPPER
- UUID4
- UUID_UNPARSE
- VARIANCE

Transformation Language Reference

10.4.0
- 10.5.6
- 10.5.4
- 10.5.1
- 10.5

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REG_EXTRACT

Extracts subpatterns of a regular expression within an input value. For example, from a regular expression pattern for a full name, you can extract the first name or last name.

Use the REG_REPLACE function to replace a character pattern in a string with another character pattern.

Syntax

REG_EXTRACT( subject, 'pattern', subPatternNum )

The following table describes the arguments for this command:

Argument	Required/ Optional	Description
subject	Required	String datatype. Passes the value you want to compare against the regular expression pattern.
pattern	Required	String datatype. Regular expression pattern that you want to match. You must use perl compatible regular expression syntax. Enclose the pattern in single quotation marks. Enclose each subpattern in parentheses.
subPatternNum	Optional	Integer value. Subpattern number of the regular expression you want to match. Use the following guidelines to determine the subpattern number: no value or 1. Extracts the first regular expression subpattern. 2. Extracts the second regular expression subpattern. n. Extracts the n th regular expression subpattern. Default is 1.

Using perl Compatible Regular Expression Syntax

You must use perl compatible regular expression syntax with REG_EXTRACT, REG_MATCH and REG_REPLACE functions.

The following table provides perl compatible regular expression syntax guidelines:

Syntax	Description
. (a period)	Matches any one character.
[a-z]	Matches one instance of a character in lower case. For example, [a-z] matches ab. Use [A-Z] to match characters in upper case.
\d	Matches one instance of any digit from 0-9.
\s	Matches a whitespace character.
\w	Matches one alphanumeric character, including underscore (_)
()	Groups an expression. For example, the parentheses in (\d-\d-\d\d) groups the expression \d\d-\d\d, which finds any two numbers followed by a hyphen and any two numbers, as in 12-34.
{}	Matches the number of characters. For example, \d{3} matches any three numbers, such as 650 or 510. Or, [a-z]{2} matches any two letters, such as CA or NY.
?	Matches the preceding character or group of characters zero or one time. For example, \d{3}(-{d{4})? matches any three numbers, which can be followed by a hyphen and any four numbers.
* (an asterisk)	Matches zero or more instances of the values that follow the asterisk. For example, *0 is any value that precedes a 0.
+	Matches one or more instances of the values that follow the plus sign. For example, \w+ is any value that follows an alphanumeric character.

For example, the following regular expression finds 5-digit U.S.A. zip codes, such as 93930, and 9-digit zip codes, such as 93930-5407:

\d{5}(-\d{4})?

\d{5} refers to any five numbers, such as 93930. The parentheses surrounding -\d{4} group this segment of the expression. The hyphen represents the hyphen of a 9-digit zip code, as in 93930-5407. \d{4} refers to any four numbers, such as 5407. The question mark states that the hyphen and last four digits are optional or can appear one time.

Converting COBOL Syntax to perl Compatible Regular Expression Syntax

If you are familiar with COBOL syntax, you can use the following information to write perl compatible regular expressions.

The following table shows examples of COBOL syntax and their perl equivalents:

COBOL Syntax	perl Syntax	Description
9	\d	Matches one instance of any digit from 0-9.
9999	\d\d\d\d or \d{4}	Matches any four digits from 0-9, as in 1234 or 5936.
x	[a-z]	Matches one instance of a letter.
9xx9	\d[a-z][a-z]\d	Matches any number followed by two letters and another number, as in 1ab2.

Converting SQL Syntax to perl Compatible Regular Expression Syntax

If you are familiar with SQL syntax, you can use the following information to write perl compatible regular expressions.

The following table shows examples of SQL syntax and their perl equivalents:

SQL Syntax	perl Syntax	Description
%	. *	Matches any string.
A%	A.*	Matches the letter “A” followed by any string, as in Area.
_	. (a period)	Matches any one character.
A_	A.	Matches “A” followed by any one character, such as AZ.

Return Value

Returns the value of the n
th subpattern that is part of the input value. The nth
subpattern is based on the value you specify for subPatternNum.

NULL if the input is a null value or if the pattern is null.

Example

You might use REG_EXTRACT in an expression to extract middle names from a regular expression that matches first name, middle name, and last name. For example, the following expression returns the middle name of a regular expression:

REG_EXTRACT( Employee_Name, '(\w+)\s+(\w+)\s+(\w+)',2)

Employee_Name	Return Value
Stephen Graham Smith	Graham
Juan Carlos Fernando	Carlos

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Table of Contents

Transformation Language Reference

Transformation Language Reference

REG_EXTRACT

REG_EXTRACT

Syntax

Using perl Compatible Regular Expression Syntax

Converting COBOL Syntax to perl Compatible Regular Expression Syntax

Converting SQL Syntax to perl Compatible Regular Expression Syntax

Return Value

Example