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Access 2010: Queries in Depth

Finding duplicate records


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Access 2010: Queries in Depth

with Adam Wilbert

Video: Finding duplicate records

In the Query Wizard we've seen that there are options beyond the simple Select query. One of those is the Find Duplicates query. The Find Duplicates query is a specific query type that will locate duplicate records within your database. This can be used for cleaning up your data tables or reviewing records with multiple entries. We can create one by going to the Create tab and using the Query Wizard. I'll select the Find Duplicates Query Wizard and say OK. The first screen ask us which table or query do you want to search for duplicate fields.
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  1. 9m 9s
    1. Welcome
      1m 10s
    2. Using the exercise files
      41s
    3. Introducing the database
      4m 29s
    4. Previewing the course
      2m 49s
  2. 17m 17s
    1. Understanding queries
      3m 31s
    2. Following naming conventions and best practices
      2m 56s
    3. Using the Query Wizard
      5m 21s
    4. Exploring the design interface
      5m 29s
  3. 26m 39s
    1. Defining criteria
      5m 40s
    2. Understanding comparison operators
      3m 19s
    3. Defining the column headers
      2m 49s
    4. Exploring the property sheet
      7m 32s
    5. Printing query results
      2m 41s
    6. Working with joins
      4m 38s
  4. 14m 14s
    1. Understanding parameter queries
      4m 27s
    2. Obtaining parameters from forms
      5m 17s
    3. Creating a combo box
      4m 30s
  5. 23m 24s
    1. Understanding the Totals field
      5m 31s
    2. Creating aggregate calculations
      3m 31s
    3. Exploring the Expression Builder interface
      4m 28s
    4. Using mathematical operators
      5m 46s
    5. Applying text functions
      4m 8s
  6. 24m 23s
    1. Understanding dates as serial numbers
      2m 42s
    2. Specifying a range of dates or times
      3m 47s
    3. Formatting dates
      4m 31s
    4. Using other Date/Time functions
      3m 47s
    5. Defining today's date
      2m 41s
    6. Calculating time intervals
      6m 55s
  7. 20m 9s
    1. Introducing the conditional IIf function
      2m 57s
    2. Creating an IIf function
      7m 31s
    3. Nesting IIf functions
      4m 57s
    4. Using the Switch function
      4m 44s
  8. 20m 41s
    1. Understanding the reporting tool
      2m 13s
    2. Building the form
      6m 57s
    3. Building the query
      5m 4s
    4. Building the report
      3m 30s
    5. Finalizing the reporting tool
      2m 57s
  9. 25m 37s
    1. Finding duplicate records
      2m 17s
    2. Identifying unmatched records
      2m 29s
    3. Creating crosstab results
      2m 57s
    4. Creating backups
      1m 29s
    5. Creating update queries
      3m 22s
    6. Making, deleting, and appending records
      5m 36s
    7. Uniting tables
      3m 16s
    8. Embedding SQL code in queries
      4m 11s
  10. 1m 0s
    1. Next Steps
      1m 0s

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Access 2010: Queries in Depth
3h 2m Intermediate Jun 16, 2011

Viewers: in countries Watching now:

In this course, author Adam Wilbert illustrates how to create and leverage real-world queries and turn raw data into usable information. The course covers setting up queries, performing calculations, using the built-in Access functions to further refine query results, and identifying top performers or areas for improvement based on a range of criteria.

Topics include:
  • Naming conventions and best practices
  • Working with joins
  • Using comparison operators
  • Defining criteria for select queries
  • Creating parameter queries
  • Creating calculated fields
  • Working with dates and times
  • Using the Expression Builder
  • Creating conditional statements
  • Making, deleting and appending records
  • Building reports
Subjects:
Business Databases
Software:
Access Office
Author:
Adam Wilbert

Finding duplicate records

In the Query Wizard we've seen that there are options beyond the simple Select query. One of those is the Find Duplicates query. The Find Duplicates query is a specific query type that will locate duplicate records within your database. This can be used for cleaning up your data tables or reviewing records with multiple entries. We can create one by going to the Create tab and using the Query Wizard. I'll select the Find Duplicates Query Wizard and say OK. The first screen ask us which table or query do you want to search for duplicate fields.

We're going to look at our Orders table. The second screen asks which field might contain duplicate information. Let's identify all of our orders where we had the same customer placed two orders on the same day. We'll choose OrderDate and CustomerID. Let's go ahead and say Next. This window asks, do you want the query to show fields in addition to those with duplicate values? Let's add OrderID so we have a reference point in case we do have duplicate values. I'll go ahead and say Next and I'll accept the default name and say Finish.

Access shows us that we do have duplicate values. I've got two orders placed by the same customer on February 9th, 2005 and an additional two orders placed by a different customer on 11/14/2009. Each order has its own unique OrderID number. Let's go ahead and modify this query a little bit so we have some more information. We'll go to the Home tab and switch back to Design view. Now, let's add our customer name and phone number so that we can call the customer and see if they really intended to place two orders or if it was a mistake.

I'll right-click and say Show Table and we'll add our DirectCustomers table. Now, Access already identified that the CustomerID matches in both tables and creates the join. We'll add FirstName and LastName and phone number to our query. Let's run it again. Now, we can see the customers that placed those duplicate orders. We have an easy way of calling the customer and find out if it's a mistake, or if they did intend to place two orders. So Find Duplicates can be really handy in keeping your database clean and organized.

Sorting out data entry errors that can often arise from importing tables from external sources is another perfect use for Find Duplicates.

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