ColdFusion Query of Queries (Streamline your Processes)

ColdFusion's Query of Queries (QoQ) is a critical, high-performance feature that enables you to execute standard SQL against existing, in-memory query results (known as a recordset). This technique radically boosts application efficiency by significantly reducing external database load, decreasing network latency, and making complex data manipulation—like joining data from different databases or creating summary reports—incredibly fast. Whether you are manipulating cached results, performing convenient table recall, or simply seeking better performance, mastering QoQ is essential for robust ColdFusion development. If your team needs expertise to fully leverage QoQ and other advanced features, consider our dedicated ColdFusion Development Services or specialized ColdFusion Consulting to optimize your processes and achieve maximum scalability.

1. What is a ColdFusion Query of Queries?
2. What are the benefits of using a ColdFusion Query of Queries?
3. How do you conduct a ColdFusion query of queries?
4. What are some functionalities of ColdFusion Query of Queries?

Finding detailed information in an extensive database can sometimes be a daunting task.

Fortunately, with ColdFusion, you make your searches and data pull a breeze with Query of Queries! Utilizing this excellent function is sure to make any CIO or Project Leader’s job easier.

 

Let’s dive right in!

What is a ColdFusion Query of Queries?

A Query of Queries is a unique feature in its respect because you can’t have one without, well, queries. You see, after you have created a recordset with a tag or function (such as cfquery), data can be recalled. It may be recalled individually or as part of a dependent query.

That recall is known as a Query of Queries. Any query that retrieves data from a recordset is a Query of Queries. It can also be known as a Memory Query because recordsets can be formed in other ways than the cfquery tag.

ColdFusion QoQ can also be used for other queries. For example, you can query a non-query database object.
It’s a super handy feature that has many benefits.

ColdFusion Query of Queries Benefits

Let’s take a look at a few of the benefits of ColdFusion QoQ.

Convenient Table Recall

There are times when you need to recall the same tables repeatedly, and the bigger the table, the more frustrating it can be. However, ColdFusion QoQ makes things easier because the data is already in the record set. QoQ is perfect for tables between 5000 and 50000 rows. Its only limitation is the memory of the ColdFusion host computer.

Join and Union Operations

Using QoQ allows you to perform join and union operations on results from entirely different databases. This can definitely come in handy. For instance, you can use a union operation on queries from separate databases in order to eliminate duplicates from an email list of clients.

Manipulation of Cached Query Results Made Easy

This is particularly useful for CIOs and Team Leaders. After performing a query on a database just once, your results can be used to generate many different tables. This comes in handy for creating summary tables for employee salaries, infographics, or availabilities. Just make a single query to your employee database and use the results given to generate three separate tables from just one pull.

Caching Database Results

Wouldn’t it be nice to have drill-down details on things without having to access a database? You can do this by using QoQ. For instance, you can pull a query on employee information using QoQ and then cache it. Afterward, create a table or drop-down list of employee names.

This way, when users select a particular employee name, your application accesses the cached data without needing to call the database.

Generating Subreport Data

Subreports are an excellent way to nest a report inside your other reports. This can become a very convenient way to post secondary information within your primary presentation. Subreports are great if you wish to avoid using complex SQL or if your report requires data from multiple data sources. QoQ helps you to generate these subreports and streamline your reports.

How to Successfully Conduct a ColdFusion Query of Queries

Conducting a ColdFusion QoQ is a pretty simple process. Just follow these four easy steps:

1. Create a recordset through a master query. Master queries may be generated through tags or functions that create recordsets.
2. Compose a detailed query. This would be a cfquery tag that specifies dbtype= “query”
3. Write an SQL statement that retrieves the applicable information. A data source does not need to be specified at this point. However, select the names of one or more currently existing queries as table names within your SQL code.
4. Your database content should be changing rapidly. But if it doesn’t, manipulate the cachedwithin attribute of your master query to cache queries between page requests. Use the CreateTimeSpan function (in days, hours, minutes, and seconds format) to specify the value. Doing so allows your ColdFusion to access the database on the first request. The database will only be queried again after the set time has expired.

Adobe provides an excellent example of how to create and use these results.

<h1>Employee List</h1>

<!— LastNameSearch (normally generated interactively) —>

<cfset LastNameSearch=”Doe”>

<!— Master Query —>

<cfquery datasource=”cfdocexamples” name=”master”

cachedwithin=#CreateTimeSpan(0,1,0,0)#>

SELECT * from Employee

</cfquery>

<!— Detail Query (dbtype=query, no data source) —>

<cfquery dbtype=”query” name=”detail”>

SELECT Emp_ID, FirstName, LastName

FROM master

WHERE LastName=<cfqueryparam value=”#LastNameSearch#”

cfsqltype=”cf_sql_char” maxLength=”20″></cfquery>

<!— output the detail query results —>

<p>Output using a query of query:</p>

<cfoutput query=detail>

#Emp_ID#: #FirstName# #LastName#<br>

</cfoutput>

<p>Columns in the master query:</p>

<cfoutput>

#master.columnlist#<br>

</cfoutput>

<p>Columns in the detail query:</p>

<cfoutput>

#detail.columnlist#<br>

</cfoutput>

Querying a Non-Database Query Object

One of the best things about QoQ is that you can query a non-database query object. An example of this is retrieving the results of a <cfftp> directory listing.

Functionalities of ColdFusion Query of Queries / CFQuery

ColdFusion QoQ has many functionalities, and their relation to QoQ is as follows:

• Dot Notations

  • QoQ supports using Dot Notation in table names.

• Joins

  • QoQ supports joins between two tables.

• Unions

  • A UNION operator allows you to combine the results of two or more SELECT expressions into a single recordset.

• Conditional Operators

  • QoQ allows you to take advantage of many different conditional operators , including:
    • Test Conditional
    • Null Conditional
    • Comparison Conditional
    • BETWEEN Conditional
    • IN Conditional
    • LIKE Conditional

• Managing Data Types for Columns

  • QoQ requires that every column must have defining metadata. Queries created with the QueryNew function that omit the second parameter do not contain metadata. Use the optional second parameter to define data types.

• Using the CAST Function

  • Use QoQ to convert a column value into a correct expression of the proper data type.

• Using Aggregate Functions

  • Use these functions ftorretrievesummary information from a table instead of retrieving the entire table and then operating on its recordset.

• Using group by and having expressions

  • QoQ supports the use of any arithmetic expression as long as it is referenced via alias.

• Using ORDER BY clauses

  • QoQ supports ORDER BY clauses as long as it is the last clause in your SELECT statement.

• Using Aliases

  • QoQ supports the use of database column aliases. You can also reuse an alias in the same SQL statement.

• Handling Null Values

  • QoQ uses Boolean logic to handle conditional expressions. The proper handling of NULL values requires the use of ternary logic.

• Concatenating Strings

  • QoQ supports two string concatenation operators: + and ||

• Escaping Reserved Keywords

  • QoQ supports a large arrangement of reserved keywords but does not support nested escapes.

• Using QoQ with Dates

  • Suppose you create a query object with the QueryNew function and populate a column with date constants. In that case, ColdFusion stores the dates as a string inside the query object until a Query of Queries is applied to the query object. When ColdFusion applies a Query of Queries to the query object, it converts the string representations into date objects.

ACF vs Lucee QoQ

ACF and Lucee QoQ are very similar, but there are several differences due to the SQL engines used in each CFML engine. These differences are more apparent in complex SQL statements, such as grouping functions. A simple rewrite of the SQL code should solve most of the complications with Lucee QoQ.

Summary?

ColdFusion Query of Queries is an excellent tool that makes your CF life a whole lot more convenient. It streamlines your processes and creates elegant output that you and your company can easily use.

When have you found query of queries to be most helpful? What practical applications do you use it for?

Let us know in the comments below. Iff you like what you read, you can always follow us on Twitter @CFTeraTech to ensure you don’t miss an update.

Cheers!

And to continue learning how to make your ColdFusion apps more modern and alive, I encourage you to download our free ColdFusion Alive Best Practices Checklist.

Because… perhaps you are responsible for a mission-critical or revenue-generating CF application that you don’t trust 100%, where implementing new features is a painful ad-hoc process with slow turnaround even for simple requests.

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And if you are depending on ColdFusion for your job, then you can’t afford to let your CF development methods die on the vine.

You’re making a high-stakes bet that everything is going to be OK using the same old app creation ways in that one language — forever.

All it would take is for your fellow CF developer to quit or for your CIO to decide to leave the (falsely) perceived sinking ship of CFML and you could lose everything—your project, your hard-won CF skills, and possibly even your job.

Luckily, there are a number of simple, logical steps you can take now to protect yourself from these obvious risks.

No Brainer ColdFusion Best Practices to Ensure You Thrive No Matter What Happens Next

ColdFusion Alive Best Practices Checklist

Modern ColdFusion development best practices that reduce stress, inefficiency, project lifecycle costs while simultaneously increasing project velocity and innovation.

√ Easily create a consistent server architecture across development, testing, and production

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Learn about these and many more strategies in our free ColdFusion Alive Best Practices Checklist.

 

ColdFusion Query of Queries (QoQ) FAQ Section

What is the main purpose of using ColdFusion Query of Queries (QoQ)?

The primary purpose of a ColdFusion Query of Queries is to manipulate, filter, and sort data retrieved from a database after the initial data pull, without making additional trips to the original database server. This is an essential technique for caching database results and improving application performance, especially when performing multiple operations on a single dataset. According to the Query of Queries user guide on the Adobe Help Center, QoQ allows developers to re-query an existing record set already held in memory on the ColdFusion server.

What are the key benefits of using QoQ for data manipulation?

QoQ offers several performance and flexibility benefits:

• Reduced database load: It minimizes database round trips, as subsequent queries execute against the in-memory query object rather than the database. This is a crucial element of Performance Optimization and Server Tuning which is one of our core services.
• Cross-Database Operations: You can perform JOIN and UNION operations on results pulled from entirely different databases, which is not possible with standard SQL.
• Simplified Reporting: It makes generating complex reports easy by allowing you to create multiple summary tables or subreports from a single, initial master query.

Does ColdFusion Query of Queries support standard SQL joins?

ColdFusion Query of Queries only supports joins through the WHERE clause syntax.

It is important to note that the QoQ engine does not support standard SQL joins using INNER JOIN or OUTER JOIN keywords. If you need full outer join functionality, you must perform that join in the original database query before it is stored as a ColdFusion query object.

How do I implement a ColdFusion Query of Queries?

A Query of Queries is implemented by following two main steps:

1. Master Query: Execute a standard <cfquery> with a datasource attribute to fetch the data from the database into a named query object (e.g., name="masterQuery").
2. Detail/QoQ Query: Execute a second <cfquery> using the attribute dbtype="query" and reference the name of your master query in the FROM clause.

Example Code:

<cfquery name="allUsers" datasource="cfdocexamples">
    SELECT UserID, Name, Status FROM Users
</cfquery>

<cfquery name="activeUsers" dbtype="query">
    SELECT UserID, Name
    FROM allUsers
    WHERE Status = 'Active'
</cfquery>

Can QoQ be used with modern ColdFusion Component (CFC) development?

Yes, ColdFusion Query of Queries can be used in modern script-based development, but the syntax requires you to explicitly pass the master query object. When using the script-based component, such as ColdFusion 9's Query.cfc, the query object must be passed as a named argument to the QoQ instance, because the QoQ execution context is separate from the calling page's Variables scope.

Example using Query.cfc (Script Syntax):

<cfset detailQuery = new Query(
    sql="SELECT Name FROM masterQuery WHERE City='London'",
    dbtype="query",
    masterQuery=masterQuery 
)/>
<cfset results = detailQuery.execute().getResult()/> 

Is Query of Queries a read-only operation?

Yes, Query of Queries is a read-only operation. It is designed for manipulating existing data and cannot be used to execute data modification language (DML) statements such as INSERT, UPDATE, or DELETE on the underlying database tables. For these operations, a regular <cfquery> with a standard datasource is required. If you require assistance with ensuring your data is handled securely and efficiently, explore our ColdFusion Consulting Experts & Agency Services.