We've enhanced our Microsoft Access Query Help Center with a new paper describing Microsoft Access Append (Insert) Queries, and how to use them to add multiple records or a single record to a table.

We also discuss why rather than using a Make Table query, it's preferable to use an existing table, empty it, then fill it with an Append query.

The purpose of the SQL UNION query is to combine the results of two or more queries into a single result set. The list contains all the rows belonging to all the queries in the union. This applies to queries in SQL Server or Microsoft Access. A common question is whether to use the UNION or UNION ALL syntax.

The main difference between UNION ALL and UNION is that, UNION only selects distinct values and sorts the results, while UNION ALL selects all values (including duplicates) without sorting. Read our revised paper on UNION versus UNION ALL SQL Syntax to learn more about the differences, see some examples, and understand why you would use one versus the other.

For more tips and using queries, visit our Microsoft Access Query Help Center.

Microsoft Access Queries are among the most powerful features of MS Access. We have created a new resource center to make it easy to review all our papers related to Microsoft Access Queries. These original works offer tips and techniques aren't found anywhere else. They will help you maximize your use of Microsoft Access queries to better analyze and understand your data. 

In the Microsoft Access Query Help Center you will find papers covering:

Retrieving Records

• Microsoft Access Query Tips and Techniques (SQL and VBA)
• Microsoft Access and SQL Server Database Normalization Tips
• Using a Microsoft Access Crosstab Query to Create Monthly SUmmery Reports without Code and modifing data
• Difference Between "Unique Values" (SELECT DISTINCT) and "Unique Records" (SELECT DISTINTROW) in Microsoft Access Queries
• Finding Records in One Table but Not Another with "Not In" Queries

Modifying Data

• Microsoft Access Update Query, SQL Syntax, Examples and Errors
• Microsoft Access Delete Query, SQL Syntax, Examples and Errors
• This Recordset is not updateable: Dealing with Non-Updateable Microsoft Access Queries
• Suppress Warning Messages When Running Microsoft Access Action Queries Programmatically in VBA
• Returning the Number of Records or Rows Affected by an Action Query in Microsoft Access with VB6/VBA

Let us know what additional related topics you'd like us to add in the future.

In our continuing coverage of query tips and techniques, we've create a paper focused on the DELETE query in Microsoft Access. It covers the basics of DELETE query SQL Syntax. It's a very powerful feature and a fundamental part of relational databases since you can remove multiple records at one time, and can specify which records to delete by linking to data in another table.

The paper also covers these more advanced topics:

• Query fails: "Could not delete from the specified tables"
• Use DISTINCTROW with Delete Queries for Non-Key Field Joins

Understanding and using Delete Queries improves the performance of your applications and makes them easier to maintain versus doing the same changes manually or in code.

Here's another resource in our ongoing coverage of query techniques:

Learn how to create queries to find all the records in one table that don't have corresponding records in another table. If you're not familiar with the difference between INNER JOIN, OUTER JOIN, LEFT JOIN and RIGHT JOIN, check out this new paper on these important query feature. It'll save you tons of time trying to code this yourself and will surely give you new ideas on how to better retrieve and analyze your data. The techniques apply to both Microsoft Access and SQL Server queries.

Here's an additional paper related to our ongoing coverage of queries. This time we're covering DELETE query syntax in Microsoft Access. In addition to the basics of deleting data and the SQL for DELETE queries, we also cover an interesting situation when DELETE queries fail during multi-table links on non-keyed fields.

If your query fails to delete any records with this message: "Could not delete from the specified tables", learn why and how to fix it with the DISTINCTROW syntax or setting the Unique Records property to Yes.

For more information on queries in general, read our paper on Microsoft Access Query Tips and Techniques.

Related to our detailed paper on Query Tips and Techniques, we added extra information on the basics and syntax of an Update Query in Microsoft Access.

We also have a related article on dealing with non-updatable queries: Error 3073: Operation must use an updatable query: Dealing with Non-Updateable Queries and the Use of Temporary Tables in Microsoft Access

Microsoft recently added three of our technical papers to their MSDN (Microsoft Developer Network) web site:

• Microsoft Access Query Tips and Techniques
• Error Handling and Debugging Tips and Techniques for Microsoft Access, VBA, and Visual Basic 6 (VB6)
• Microsoft Access Performance Tips to Speed up Your Access Databases

We're proud Microsoft recognized our work and look forward to sharing more resources with the developer community.

When creating queries in Access, you may have noticed the query properties "Unique Values" and "Unique Records". Are you familiar with the difference between these properties?

"Unique Values" and "Unique Records" correspond with the DISTINCT and DISTINCTROW statements (respectively) in the query's SQL. Although they sometimes provide the same results, there are significant differences in how they work:

• DISTINCT checks for unique values only in the fields selected for output, and eliminates duplicate rows. Results are not updateable, since they do not necessarily correspond with a unique record.
• DISTINCTROW checks for unique values in all fields in the table that you are querying, not just the fields listed for output. Results are updateable, since they correspond with a single record in the underlying data.

Learn more and view an example of the differences in our new paper on Microsoft Access Queries: Distinct versus DistinctRow.