How to Efficiently Split Comma-Separated Values with Nulls into Multiple Columns in Oracle?

Oracle: Splitting Comma-Separated Values into Multiple Columns

This article addresses the challenge of efficiently splitting comma-separated values (CSV) in Oracle SQL, particularly when dealing with null or empty elements within the CSV string. Standard approaches using REGEXP_SUBSTR can fail in these cases.

A robust solution utilizes a refined regular expression pattern: (.*?)(,|$). This pattern effectively handles nulls and empty entries. Let's break down the pattern:

1. (.*?): This part captures any character (.) zero or more times (*), non-greedily (?). This ensures that only the characters up to the next comma (or end of string) are captured.
2. (,|$): This matches either a comma (,) or the end of the string ($). This acts as the delimiter, separating each value.

This improved pattern guarantees accurate extraction of values, even with nulls or empty entries within the CSV string. For instance, to extract the fifth value from the string '1,2,3,,5,6', use this query:

REGEXP_SUBSTR('1,2,3,,5,6', '(.*?)(,|$)', 1, 5, NULL, 1)

This approach avoids the common error of retrieving incorrect values when nulls are present, providing a reliable method for parsing CSV data in Oracle.

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