#SQL

Date range queries going too slow for you? SQL Performance got you down? I have one weird trick that might just help you out! (SQL Developers hate this!)*

If you have a class that records timestamps when the data is added, then that data will be in sequence with your IDKEY values - that is, TimeStamp₁ < TimeStamp₂ if and only if ID₁ < ID₂ for all IDs and TimeStamp values in table - then you can use this knowledge to increase performance for queries against TimeStamp ranges. Consider the following table:

I have a class that writes to an external SQL Server database. When the field is empty, it does not write the column and the column has the value NULL. In some cases, I want the column to be the value of the empty string instead of NULL.

The Caché System Management Portal includes a robust web-based SQL query tool, but for some applications it’s more convenient to use a dedicated SQL client installed on a user’s PC.

SQuirreL SQL is a well known open source SQL client built in Java, which uses JDBC to connect to a DBMS. As such, we can configure SQuirreL to connect to Caché using the Caché JDBC driver.

Class Queries in InterSystems IRIS (and Cache, Ensemble, HealthShare) is a useful tool that separates SQL queries from Object Script code. Basically, it works like this: suppose that you want to use the same SQL query with different arguments in several different places.In this case you can avoid code duplication by declaring the query body as a class query and then calling this query by name. This approach is also convenient for custom queries, in which the task of obtaining the next row is defined by a developer. Sounds interesting? Then read on!

The Art of Mapping Globals to Classes 1 of 3

Looking to breathe new life into an old MUMPS application? Follow these steps to map your existing globals to classes and expose all that beautiful data to Objects and SQL.

Error:

[SQLCODE: <-400>:<Fatal error occurred>]
[Cache Error: <<SUBSCRIPT>%0AmEdun+4^%sqlcq.HSREGISTRY.cls966.1 ^||%sql.temp(1,"")>]
[Location: <ServerLoop - Query Fetch>]
[%msg: <Unexpected error occurred: <SUBSCRIPT>%0AmEdun+4^%sqlcq.HSREGISTRY.cls966.1 ^||%sql.temp(1,"")>]

Here is an example of a query that gives the error:

SELECT COUNT(DISTINCT Criteria) as Relevance FROM HS_IHE_ATNA_Repository.Aggregation
WHERE EventType = 'CROSS GATEWAY QUERY'

As we all know, Caché is a great database that accomplishes lots of tasks within itself. However, what do you do when you need to access an external database? One way is to use the Caché SQL Gateway via JDBC. In this article, my goal is to answer the following questions to help you familiarize yourself with the technology and debug some common problems.

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.

Introduction

In the first article in this series, we’ll take a look at the entity–attribute–value (EAV) model in relational databases to see how it’s used and what it’s good for. Then we'll compare the EAV model concepts to globals.

Hi,

My doubt is about the SQL Query in Caché:

I don't want to take all results from the table and orgainze them manually, for example: I have a table with 50 records, but I only want to select 10 records, being from tenth until the twentieth and this without knowing their IDs.

So, how can I do this, without losing performance, there is any way?

I am trying to make architecture for my project. And for it, it needs to make list property in which there is list of objects of another table, the data must be unique, therefore I make sql-query to check objects of another table if it is used or not, but I can't make sql-query to check elements in list in property with elements of another table. Can you help me? In property ID of object is used.

Would like to know if there is an alternative or better way to paginate through a dataset using dynamic SQL than what I am using below. The problem is that as the potential pool of data gets larger, this code slows down to the point of not being useable. In analyzing each line of code below, it appears the slow down is related to the initial rset.%Next() iteration. Is there anything available which does not require a subquery/%VID such as a simple LIMIT/OFFSET?

My code is similar to :

s sql=##class(%SQL.Statement).%New()

Trackcare 2021.2

Please may I know how to access SQL parameter with string as datatype with NO reference to SQL Table and SQL Column.

Hi Experts,

I have these two clarifications to make:

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.MessageHeader