How to convert Query column to a list in ColdFusion

Question

I'm trying to convert ColdFusion query column to a list, what is the best way to do so?

I thought that there is a built in function that allows one to easily convert a query's column in to a list, if there is what is it?

Solution 1

There is a built-in function to do that: ValueList

<cfset myList = ValueList(query.columnname)>

As with all of the list functions, there's an optional delimiter attribute.

<cfset myList = ValueList(query.columnname,"|")>

If you need the values in the list to have double-quotes around them, use QuotedValueList.

<cfset myList = QuotedValueList(query.columnname)>

Solution 2

You can also access a query's columns as arrays directly without any conversion if that works for what you're trying to do:

qry.col[1] // col field of first record
qry.col[2] // col field of second record
...

or

qry["col"][1] // col field of first record
qry["col"][2] // col field of second record

A CF query object is really an associative array of columns... weird but occasionally useful.

Solution 3

How about in a case like this:

<cfset SummaryQuery = Evaluate('getReportData' & summaryName & 'Summary') />
<cfset TypeList = ArrayToList(SummaryQuery[subsectionName & 'Type']) />

vs.

<cfset QueryColumn = SummaryQuery[subsectionName & 'Type'] />
<cfset TypeList = ValueList(QueryColumn) />

Comments

[Tyler Clendenin]

Erik, your question is a bit old so you prolly already figured it out, but for posterity: ArrayToList(QueryName["ColumnName"], ",")

[Tyler Clendenin]

Even though this is closed, don't know why, I feel compelled to place this answer, ArrayToList(QueryName["ColumnName"], ",").

[ale]

Why in the world are you offering these convoluted solutions? What's wrong with ValueList()?

[bpanulla]

Treating the column as an array requires no conversion and is faster for large recordsets. ValueList() takes some non-zero amount of time to convert, and what you get out of it is a string. Working with a string list now takes even more time. Why convert something from an array to a list and then back to some sort of iterable construct just to use it again?

[ale]

@bpanulla: Fair enough, but the asker did specifically ask for a list.

[bpanulla]

If the poster asked "what's the best pair of scissors to use to cut down a tree?" wouldn't you feel obliged to suggest a chainsaw? Just saying ;)

[ale]

Well, asking "what's the best" anything is a subjective question and likely to be closed, but I get your meaning.

[David Faber]

One might want a list to use in a future query with an IN clause. I've done this in CF many times to avoid using CFQUERY within a loop over another query.

[Jared Beck]

-1 because this answer is misleading. Using dot-notation on a query does not actually return an array. IsArray(qry.col) returns false. You can access cells with [] but it's not actually a CF array.

[Matthew Friedman]

why not just used the built in function query.ColumnList

[ale]

@MatthewFriedman: query.ColumnList gives you a list of the columns. ValueList() gives you a list of the value in every row for a specific column. Two very different usecases.