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What is VRML?

Question: I’ve heard a lot about VRML, but don’t know what it is. Please explain. Answer: VRML (Virtual Reality Markup Language) is a method for sending 3D data across the

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Finding Two Equal Sets of Data

Question: [Joe Celko’s Equal Sets Puzzle]Set theory has two symbols for subsets. One is a “horseshoe” on its side, which means that set A is contained within set B and

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Dataflow Diagrams

Question: [Joe Celko’s Dataflow Diagrams Puzzle]Tom Bragg posted a version of this problem on the CASE Forum on CompuServe. You have a table of dataflow diagrams (DFDs), which has the

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Pivoting Table Data — Horizontal Display

Question: [Joe Celko’s Milestones Puzzle]This puzzle, in a little different form, came from Brian Young. His system tracks a series of dates (milestones) for each particular type of service (tos)

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Finding Exactly Two of Three — Conditions

Question: We are putting together a book with contributions from many Anthologies (identified by their contrnum). We want to find all Anthologies thathave articles in exactly two out of three

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Finding Unique Data

Question: How would I change the following statement to yieldonly unique values? select * FROM WEBDBASE where ST = ‘#State#’ AND #SPECIALTY# = ‘x’; Answer: You can’t get unique values

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Pattern Matching

Question: How can I use SQL to specify a query like the example below: select * from mytable where column like ‘a[bc]’This should match both “ab” and “ac” but not

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GROUP BY: Sorting with an Additional Column

Question: How do I arrange to sort within a GROUP BY clauserather than over the complete result set, e.g. L0 PDV …… L90 PDV …… L180 PDV …… L270 PDV

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Matching Employees’ Skills with Jobs

Question: [Joe Celko’s Employment Agency Puzzle]You are running an employment agency that has requests for jobs and applications from candidates. Both of these forms include a list of the skills

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Calculating Hourly Billings

Question: [Joe Celko’s Consultants Puzzle]Brian K. Buckley posted a version of the following problem on the PowerSoft CompuServe forum in the WATCOM SQL section in 1994 November requesting assistance. He

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Compare Budget and Actual Tables

Question: [Joe Celko’s Budget Versus Actual Puzzle]C. Conrad Cady posted a simple SQL problem on the CompuServe Gupta Forum. He has two tables, Budgeted and Actual, which describe how a

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Finding Exactly One Non-Zero Column

Question: [Joe Celko’s One In Ten Puzzle]Alan Flancman ran into a problem with some legacy system data that had been moved over to a SQL database. The table looked like

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Delimited Data

Question: Is there a quick and dirty way to export a delimited datasetvia a simple query? I would like to get something like: value1,value2,value3(The delimeters could be commas, semi-colons, etc.)

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Finding Only the Most Current Row

Question: The Situation: I need to define some queries to extract data from an existing database (I am using MS Access 2.0). It consists of only two tables, from which

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Stored Procedures

Question: What are the common uses of stored procedures? Answer: Many databases use stored procedures and/or triggers to implementreferential integrity [ensuring that data referenced by another tabledoesn’t get deleted or

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Creating Views

Question: I’ve got a “new user” question for you. Some of the tables in our databaseshave several columns containing data that’s not used very often. When I’musing ad-hoc queries, it

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New Features

Question: What are some of the new features of Power Objects Version 2? Answer: The major new features of Version 2.0 include:New platforms – OPO will continue to support both

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Selecting multiple rows

Question: I want to let the user select more than one row in a repeater so my application can act on all of them at one time? Answer: A repeater

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Tables in a session

Question: When I open a session to my Oracle database, I can only see tables that are owned by my user name. How can I get to see other public

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Forms without MDI

Question: I want to have a form that does not appear in a MDI (multiple document interface) frame. Can I do this? Answer: In Version 2 of Power Objects, you

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Dates in String Variables

Question: I want to use a string variable with the date in it (format would be 02/22/96). How do I accomplish this? Answer: You’ll need to first convert the date

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Embedded SQL

Question: What is Embedded SQL, and howis it used with the C language? Answer: As the name implies, Embedded SQL describes SQL statements that are embedded in a host language.

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Simulating Multiple Outer Joins

Question: I need to query a database with outer joins on more thanone table, and am finding that my database doesn’t support it.Is there any way to work around the

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Combining Columns of Different Types

Question: I am doing a select from a table where I want to combine two fields. Specifically, I have the StreetNumber andthe StreetName stored separately. I would like to beable

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Inserting rows

Question: When I insert a row into a table, the results from the query that come after the row don’t show up. If I re-fetch the results, I can get

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Flushing and Locking

Question: How can I set the flushing of rows to the database or the locking strategy used by Power Objects? Answer: Oracle Power Objects ‘supports’ two ways that rows can

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Clearing menu bars

Question: I can’t seem to clear the default menus in a modal dialog box. I have triedall types of code in the OpenModal() method, but the default menusstill appear. How

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Lock failure

Question: I am using the Japanese version of OPO. Occasionally, I get an error messagethat says ‘Failed to lock row.’ It doesn’t happen all the time. What makesOPO lock a