Demo file: fm-sqlportal-filter-and-dynsort.zip (75 Mb compressed, 230 Mb uncompressed)
I’ve said before, and no doubt will say again, that one of my favorite things about this blog is how much I learn from your feedback and the demo files you send me.
Recently I received a file from Otmar Kramnis of the Hochschule Luzern demonstrating the fastest SQL-based method I have yet seen to solve the challenge we looked at in part 1 and in part 2, and with a few minor modifications, this is the demo we’re going to focus on today: Outer Join Demo 7
As you may recall, the aim is to show a week’s worth of daily sales totals for all employees whether they had any sales or not.
Or, to restate the problem in more generic terms: we need to show all values from table A, whether or not there are any matching values in table B. This is known as an “outer join”, or more precisely a “left outer join”, since we want to see all values in the “left” table (Employees), whether or not they have corresponding matches in the “right” table (Sales).
Beverly Voth has produced a PDF version of The Missing SQL Reference with some additional material not available in her original posting from October 19th.
And the SQL4_fmdev2.fmp12 demo file has been updated with new queries.
Thank you Beverly for this major contribution to the FileMaker community.
There seem to be many questions about the usage of SQL (Structured Query Language) with the ExecuteSQL function in FileMaker 12. This tutorial attempts to explain some of the SQL terms, if you are new to writing SQL statements. Since there are already many examples of how to write the ExecuteSQL queries, links to these will be listed at the end of this article. If you don’t need to learn the terms, jump right to the Helpful Example Databases section, below. There you will find links to solutions that help you create and test your queries.
This is not a complete SQL guide, as other databases may use other syntax. This is not a complete FileMaker and SQL guide, as FileMaker may be an ODBC source and the SQL queries made against it may vary from the terms used by ExecuteSQL(). This is not a complete FileMaker and ESS guide using SQL calls (if using Import or Execute SQL script steps or ExecuteSQL() function or ESS). It may not have all the nuances needed for other data sources. This is the ExecuteSQL() function reference for which you’ve been waiting. The FileMaker 12 ODBC and JDBC Guide is helpful, but it has uses outside (and beyond) the ExecuteSQL() function. Any discrepancies between the reference and the function will be noted here, if possible.
Last week in part 1 we looked at four “outer join” reporting approaches. Two of them involved ExecuteSQL, and I ended that section with the plea: Of course it’s possible that you, dear reader, know some FileMaker SQL voodoo to speed things up, and would be willing to share? Well Dr. Osamu Noda of Japan was kind enough to not only respond, but has provided a pair of demos (Outer Join Demo 5 and Outer Join Demo 6) which are significantly faster and which I am sharing with his permission.
Both of the demos are based on my original files from last week, and as you may recall, the aim was to show a week’s worth of sales for all employees whether they had any sales or not.
Recently I had an on-screen reporting challenge, and decided to try several different approaches to see which would be fastest. The challenge: Starting with two tables, one containing 20 Employees, and one containing 2,000 Sales records for the current year…
…display daily sales totals per employee in a seven-day grid, like so:
A few months ago I mentioned “dwindling value lists” in passing, and said I would do a proper article on them at some point in the future. Well, then FM 12 was released and I went on an ExecuteSQL binge, so I’m just now getting around to honoring my promise.
Dwindling Value Lists (DVLs) are value lists that shrink up, by removing individual list items as they are selected. They can come in very handy when you need to schedule resources and want to prevent double booking. This example comes from one of today’s demo files, Dwindling Value Lists, and shows how a DVL might be used to schedule employees for a work shift.
Essentially, a DVL is a filtered value list that updates in real time (or something very close to real time), and this is done by building a multiline key of selected values, and then filtering the VL to only show remaining eligible values. Continue reading “Dwindling Value Lists, part 1”
In part 1, I listed six scenarios that could potentially cause ExecuteSQL code to break:
…and managed to get through the first five before running out of steam. This time, we’re going to examine #6 on the list, and then look at a few miscellaneous odds ’n’ ends, and today’s demo file is ExecuteSQL Sandbox, v2, if you’d like to follow along.
Changing a Field Type
Why would changing a field’s type cause a problem? Well, first off, as I mentioned last month, if you are using that particular field as a predicate in a JOIN, the query will break, and your reward will be the the dreaded “?”.
I don’t have a fix for this, just some advice: Don’t change a field’s type if you’ve used it as a JOIN predicate in a working SQL statement. (The only reason I’ve needed to change a field type recently was to fix a broken JOIN where the field types were mismatched.)
The other day a colleague remarked, “You know, it’s going to be interesting to see if you SQL guys are still so excited about ExecuteSQL when something gets renamed and your code breaks.” He had a good point: code is “brittle” if it works initially, but then subsequently breaks as a result of a seemingly innocuous action.
Here are some things that can cause ExecuteSQL code to break:
- Renaming a table occurrence (TO)
- Renaming a field
- Using a “reserved word” as a field or TO name
- Having a problematic character in a field or TO name
- Executing the code in a foreign country (!)
- Changing a field’s type (e.g., from text to number or vice versa)
…and today we’re going to look at some defensive measures we can employ to prevent problems when these things occur.
Using the “orders” table in the demo file…
This is a quick follow-up to part 1, with a couple more observations about dynamic parameters.
Here’s one I can’t believe I forgot to mention the other day: A major ExecuteSQL headache that dynamic parameters can alleviate is the dreaded “embedded apostrophe” problem. In case you aren’t familiar with it, if your text string contains an embedded apostrophe, in standard SQL you must escape it by prepending another apostrophe, for example compare these two “standard” (non-dynamic) queries:
As you might expect, you don’t have to worry about this if you instead use a dynamic parameter… just quote the search term the way you would any FileMaker text string (i.e., in double quotes) and go about your business.