How to clean data using Regular Expressions in Data Quality Services?


In this blog – post, I’ll share a quick demo of how you can use Regular Expressions in Data Quality services to clean records. For the purpose of the demo, I’ll show how to clean perform a preliminary cleaning procedure on email records.

Before we begin, just a primer on Regular Expressions:

“a regular expression provides a concise and flexible means to match (specify and recognize) strings of text, such as particular characters, words, or patterns of characters. Common abbreviations for “regular expression” include regex and regexp.” – source: WikiPedia Regular Expressions

Let’s take an example:

using Regular Expressions you can:

  • check if a text starts with A or a
  • check if a text contains the word “data”
  • check if a text follows the following pattern:  something@something.something.
  • among other things..

Now, Note the power of Regular Expressions to check for a pattern like – now can we not use it to perform a basic cleaning on email records? I think, we can! and so, let’s try that:

for the purpose of the blog post, let me quickly show how you can create a Domain in a Knowledge Base that uses Regular Expressions to clean email records:

1) Open Data Quality Client > New Knowledge Base > Domain Management > create a domain

2) Switch to Domain Rules Tab

3) create a new Domain domain rule which uses the Regular Expression: [A-Za-z0-9._-]+@[A-Za-z0-9.-]+.[A-Za-z] to perform a basic cleaning on email records:

1 sql server data quality cleaning email regular expressions

4) You can use this Knowledge base to clean email records in Data Quality Records But for now,  let’s test our Regular Expression >  click Test Domain Rule > Enter few records > Test them!

2 sql server data quality cleaning email regular expressions test

Note: This is just a basic demo to show Regular Expressions in action. For cleaning Email records, there are other options like using third-party data sets or writing an advanced regular expression. The RegEx I shared was just meant for quick demo but if you want to read more about Regular Expressions used to clean emails then I will strongly recommend you to read email regular expressions that I got to know from via the discussion on a Beyond Relational Tip that I had posted.


In this blog post, we saw how to do basic cleaning on email records using regular expressions in Data Quality Services

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7 thoughts on “How to clean data using Regular Expressions in Data Quality Services?

  1. Puneet

    Hi, excellent piece.
    I want to create a domain rule to check if the 3rd character of a domain contains 1, 2, or A.
    In sql i use substring(colname, 3,1) in (‘1′,’2′,’A’) which I want to implement that in DQS. I tried Pattern match and regular expression but I can’t find what are the valid expressions for Substring match?


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