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SQL is a standard language for storing, manipulating and retrieving data in relational databases.

Question Chris Bransden · Jun 28, 2017

Hi!

I have a global-mapped class that I want to add a transient property through (or at least, not stored on the database). This property is the sum total of various charge classes that are linked to the class via child relationships.

I want this new transient property to be visible at least via SQL.

My current approach is to total it up in a ClassMethod called via SqlComputeCode. It seems to work, but feels clunky. I wonder if there is a way without passing the %%ID through? I tried it with $this but that only returns the object name in a ClassMethod.

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Question John Matson · Jul 10, 2017

Greetings,

I am working on the first of many triggers which will have identical code upon row insertion or update of a single column.  According to the document I should be able to define a multiple-event trigger using Cache SQL/DDL.

Here is a link to the current CREATE TRIGGER documentation.  Within the description section is the following paragraph:

A single-event trigger is triggered by a specified INSERT, DELETE, or UPDATE operation. A multiple-event trigger is defined to execute when any one of the specified events occurs on the specified table.

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Article Vitaliy Serdtsev · Jul 7, 2017 19m read

Quotes (1NF/2NF/3NF)ru:

Every row-and-column intersection contains exactly one value from the applicable domain (and nothing else). The same value can be atomic or non-atomic depending on the purpose of this value. For example, “4286” can be
  • atomic, if its denotes “a credit card’s PIN code” (if it’s broken down or reshuffled, it is of no use any longer)
  • non-atomic, if it’s just a “sequence of numbers” (the value still makes sense if broken down into several parts or reshuffled)

This article explores the standard methods of increasing the performance of SQL queries involving the following types of fields: string, date, simple list (in the $LB format), "list of <...>" and "array of <...>".

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Question CM Wang · Jul 5, 2017

"SELECT  %SYSTEM.SQL_TableExists('table name') "could work as expected under SQL shell,

but for   "CALL %SYSTEM.SQL_TableExists('table name')" does not work (not any error reported, it just show nothing).

Is there any reason why CALL could not be applied to a stored procedure?

Thanks.

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Question Mike Kadow · Jun 12, 2017

I would like to start a discussion regarding Caché Objects and Caché SQL.

It is my understanding that the creators of Caché Objects see Caché SQL as the reporting arm of Objects and as such SQL is essential to Caché Objects.

I once met a Caché Objects programmer who was writing code to $Order through the Globals because that person thought that Caché SQL was too slow and inefficient. I attempted to convince the person otherwise.

So, what say you? Is SQL essential to Caché Objects?

Or

Is Caché SQL a nice to have but we can do without? Is it too slow? Is it too inefficient?

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Question André Rothe · Jun 22, 2017

I try to find a function, which generates hash values of columns. In MS SQL Server I can use

select hashbytes('sha2_256', my_column) ...

to create hash values of my_column. Is it possible to use such things in Caché?

Thank you
André

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Question Nic Lorenzen · Jun 17, 2017

Hi all,

I have a non objectscript application connecting to a cache instance via ODBC and one column is a list of serial objects. The output from the query contains a lot of special characters and I'm hoping there's a better way to get this data back so I won't have to perform extensive parsing on the application side.

I've tried using the $ListToString() function, but that didn't help much, probably because the list contains complex objects rather than primitives. 

Any help will be greatly appreciated!

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Question Aditi Goswami · Jun 14, 2017

Hello,

I have a question related to running an SQL query for range of data.

I am running a query like:

Select A,B from table_name where A>=12345 AND A<=12390

 - Where A and B are my two of the properties under the mentioned table/class definition

- A is an integer property

 Question: The result of the above query does not return me all the values between the mentioned range of integer though I do have all the values in that range. I see that some of the values are missing in result.

Any reason why this query won't work?

Any ideas?

 

Thanks,
Aditi

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Article Eduard Lebedyuk · Jan 9, 2017 3m read

In addition to its general security, Caché offers SQL security with a granularity of a single row. This is called row-level security. With row-level security, each row holds a list of authorized viewers, which can be either users or roles. By default access is determined at object modification Some time ago I became interested in determining row-level security at runtime. Here's how to implement it.

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Question Glenn van Bavel · Jun 15, 2017

Whenever I try to run a simple query on a production database table, I get a timeout 504 error. I'm using the SQL interface in Ensemble. One of the queries is a simple SELECT TOP 10. Even SELECT COUNT(*) gives a timeout. 

I have tried to run the SQL Runtime Statistics, but this gives me a timeout as well. 

Does anyone have an idea where I might look to find what is causing this? 

 

Thanks in advance, 

Best regards

Glenn van Bavel, 

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Question Arockia Raj B · Jun 8, 2017

How to simply going to get the value of the system language from ^%z?  Because  I got a problem, U2 context isn't setup while connecting the SQL Connect.

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Question Rubens Silva · Jun 2, 2017

I'm breaking my head trying to figure how to solve this issue. 

When using SQL, If the column (property) is populated with at least one value and is a %List, then I can check if it's $listvalid and $listlength(column) > 0.
Now let's suppose there's no data inserted for that column on next row.
I can't simply use $listvalid because $listvalid("") = 1. Yeah, empty values is a $list for Caché.
So my question is, how do I discover if the regarding column is indeed a %List independently of being empty or not when retrieving it's value via SQL?

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Announcement Stefan Wittmann · Aug 25, 2016

As Bill has mentioned earlier in his post, we have carefully reviewed the JSON capabilities and made some adjustments to ensure they deliver the best benefit to you. In this post, I am going to describe the modifications in more detail and provide guidance for you to understand the implication for your code base.

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Question Confused Developer · May 27, 2017

I am inserting rows in a table. This table is appearing in all namespace as I did global mapping. 

So once I run insert command from a method, it insert the rows. When I run the same insert command from other namespace, it replace the existing data in table. 

Insert command is same in all namespace but the data I m inserting is different. 

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Article Michelle Stolwyk · May 25, 2017 2m read

The Data Platforms department here at InterSystems is gearing up for this year's crop of interns, and I for one am very excited to meet them all next week!

We've got folks from top technical colleges with diverse specialties from hard core engineers to pure computer scientists to mathematicians to business professionals. They come from countries around the world like Vietnam, China, and Finland and they all come with impressive backgrounds. We're sure they will do very well this summer.

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Article Brendan Bannon · Sep 1, 2016 9m read

The Art of Mapping Globals to Classes  (2 of 3)

 

If you are looking to breathe new life into an old MUMPS application follow these steps to map your globals to classes and expose all that beautiful data to Objects and SQL.

 

This example is going to cram in 4 or 5 different things beyond what was covered in Part 1 

All that is left after this is the Parent Child mapping example and then you will be on your way.

 

Same disclaimer:  If you can’t make heads or tails of your globals after reviewing these articles please contact the WRC and we will try to help you out:  Support@InterSystems.

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Question Jean Millette · Apr 20, 2017

Atelier Users:

Has anyone found an Eclipse plug-in that provides the capability to connect to a Caché server and give the user a way to write SQL queries using the tables from that server? I'm picturing something like a "WinSQL"-client built as an Eclipse plugin.

I've found and tried the following, but I couldn't get it to connect to my local Caché instance.

http://eclipsesql.sourceforge.net/

I do a lot of SQL query building with the SQL tool on the Management Portal or $system.SQL.Shell() from terminal before moving the queries into my COS code.

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Question Roger Beeman · Apr 20, 2017

Hi All -

I was wondering if the below query could be enhanced to automatically look back 24 hours from the current datetime the query is run. As is now I, of course, have to update the date range in the WHERE clause manually.

The query is just getting all MessageBodyClassNames, counting them and then doing an AVG on TimeCreated and TimeProcessed. Nothing too complex.

 

SELECT MessageBodyClassName, count(ID) as Count_Of_Messages, avg(datediff(ss, TimeCreated, TimeProcessed)) as avg_processing_time_in_seconds

FROM %PARALLEL Ens.

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Question Константин Ерёмин · Apr 20, 2017

Hi All,

I use SQL function JSON_OBJECT to get data as a JSON object.

However, sometimes I get error with function JSON_OBJECT when values contain [, ], { or }.

Error:

[SQLCODE: <-400>:<Fatal error occurred>]

Unexpected error occurred in JSON_OBJECT() function execution of <JSON_OBJECT>.%FromJSON().Parsing error

For example,

Query: SELECT JSON_OBJECT('idSQL':id, 'content':content) FROM DocBook.

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Article Kyle Baxter · Apr 12, 2017 1m read

 It's almost time to get your customers upgraded to new versions - are you worried about showing off your SQL Performance after upgrades?  If you want to upgrade without worrying, then I have just the program for you!!!  Check out this video from Global Summit 2016 featuring yours truly explaining how to upgrade a system without worrying about pesky SQL queries showing on your waistline!  

https://www.youtube.com/watch?v=GfFPYfIoR_g

Unfortunately the video started after the Frozen Musical Sing-a-long, but it's 30 minutes of the most fun you'll have while learning tools and tips for Caché

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Question Massimo Sebastiani · Mar 30, 2017

Hello, we have a few hundreds of triggers to port from Oracle to Cachè for a migration project, and many of them have to change (for example, normalize a value, null it, etc) the value which is being inserted.

The documentation says "You cannot set {fieldname*N} in trigger code." , so we're unlucky.

Is there a good workaround for this ?

SqlComputeOnChange doesn't seem the best way, but I'm not totally sure: for example normalization and validation could have a better place somewhere else than a trigger.

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Question sansa stark · Mar 22, 2017

Hi All, In Cache Table i have stored the data value as horlog format ,by query how to retrive the data when i give the data field as date format.

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Question Stella Ticker · Mar 18, 2017

I am trying to return the maximum of the value of 2 fields: LastViewed and LastDownloaded  AS a local variable -LastAccessed for each row, using a SQL query . These values are stored as $ H format.  Is there an existing SQL command that compares two column values ? I could not find one, so I tried using a $Select statement . I got an error that said A term expected beginning with either of: identifier, constant, aggregate, $$,(,:,+.

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