![]() Here's the GREATEST / LEAST documentation for MySQL, MariaDB, Oracle, and Db2 - with credit to this StackExchange post for those links. Just another crazy thing that you can do with PostgreSQL. Apparently these functions even work for strings - in effect, providing alphabetical comparison (though I don't know if that's necessarily the "right tool for the job"). Last_seen_at = GREATEST (last_seen_at, :new_value )Ĭredit where it's due - this post on EBD goes into a lot of detail, with examples, about how you can use GREATEST and LEAST - I found it practical and informative. Using GREATEST simplified the logic needed during the update process - I could use a single query to increment the count every time, but only change the "most recent" date column when a newer timestamp appeared: UPDATE my_table The logs being parsed were not in chronological order and came from various sources. This was my use case I had a table with columns tracking a value's total number of occurrences and the date/time of the latest. last_seen_at is changed only if :new_value is more recent As we can see, the UPSERT operation either updates or inserts the record into the table, and because of this reason, we call this term UPSERT (either UPDATE or INSERT). ![]() SET last_seen_at = GREATEST (last_seen_at, :new_value ) If a similar row already exists in the table, PostgreSQL will update the existing record otherwise, it will insert the record as a new entry. max_age is changed only if :new_value is largerĪs you'd expect, GREATEST can be used to compare numeric values, but I was very surprised to learn that it also works for comparing timestamps (which you wouldn't necessarily realize just by reading the documentation): - comparing date/times! SET max_age = GREATEST (max_age, :new_value ) ![]() That is, GREATEST functions almost like an if statement - update this column only if the provided value is greater than the current value: - comparing numeric values Because the greater of the two is returned, this comparison can be used to conditionally update a column. While this is helpful to know, what I found even more useful was that you can use GREATEST to compare the current value of a column with an incoming value. The GREATEST and LEAST functions select the largest or smallest value from a list of any number of expressions. I'm coming from a MS SQL Server background, so I wasn't familiar with GREATEST / LEAST, which apparently are available in most other database engines, though they are not part of the SQL standard. This operation updates an existing row in a table.A quick note on a very convenient PostgreSQL function that I learned today - GREATEST - which can be used when you want a database column updated only if the incoming value is greater (more recent) than the existing value in the column. This operation inserts a new row into a table. This operation gets tables from a database. This operation deletes a row from a table. ServerĪuthentication type to connect to your database For more information, please see the Connectors overview for canvas apps - Power Apps | Microsoft Docs Name If the power app is shared with another user, connection is shared as well. The connector supports the following authentication types: Insert row operation requires to provide explicit value for Primary Key column, even though default/autoincrement value is defined. ![]() The followings are some of the known limitations of using PostgreSQL connector: The minimun supported PostgreSQL database version is version 9.4. When installing, make sure that you select NpgSQL GAC Installation to ensure NpgSQL itself is added to your machine. The provider architecture (32-bit or 64-bit) needs to match the architecture of the product where you intent to use the connector. To install NPGSQL ADO.NET provider, go to release page and download the relevant release. PostgreSQL connector requires NPGSQL ADO.NET provider 4.0.10 to be installed. This connector is available in the following products and regions: ServiceĪll Logic Apps regions except the following:Īll Power Automate regions except the following:Īll Power Apps regions except the following: Connect to on-premise PostgreSQL database to read data from tables. PostgreSQL is a relational database management system developed by PostgreSQL Global Development Group. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |