I would like to update the value of a column within the same table by transforming its former value, but I would like to first test it with the first 10 data according to its created date. I am getting this error though Here is my sample code: Any syntax that would make this work? Answer Hmmm . . .
Tag: postgresql
Default value in select – SQL
I want to select the sum of the biggest and the lowest numbers in specific column of table, I get it well but I also need to set a default value in case if the column is empty, so far I tried this: And if my table is empty I want to get a single value with default value like
How to add a row to result if a condition based on two adjacent rows is true
Given a table like this Is it possible to get this? Right now, I’m post processing the table with a for loop checking if system_time_start is not equal to the previous row’s system_time_end, then insert another row to the result with a null price, but I’m wondering if there’s a way to do this in SQL. I was thinking to
Percentage distribution of column occurence?
I am looking for a way to calculate the distribution of column values in my table. e.g. if I have two rows containing “red” and “blue”, each should have 50%. I want to count the occurence of col and compare that to the overall amount of rows. My attempt: Any help? Thank you! Answer Just pay attention to integer division.
PostgreSql and EF – Getting ‘duplicate key’ error while doing ‘ToDictionary’ after grouping
Here is my query. UserName column is citext, having non-unique index on it. var logs = Db.Logs .GroupBy(x => x.UserName) .ToDictionary(g => g.Key, g => g.Max(m => m….
H2 vs PostgreSQL generated column with function
I’m trying to setup a generated column which will also take null checks into consideration when subtracting values. In PostgreSQL I did: ALTER TABLE session ADD COLUMN duration INTERVAL GENERATED …
How to get the average from computed columns in Postgresql?
I have a query: SELECT sum(column_1), sum(…) as sum_1, sum(…) as sum_2, sum(…) as sum_3 FROM table_1 How to get an average data from sum_1, sum_2, sum_3? If I write a query in the next …
query for many to many record matching
I have table tag_store like below I want to filter the ids which has all tag provided in a like SELECT st.id from public.”tag_store” st inner join (…
Postgresql select max query takes long time
I have the following structure in a table in my database. Below I list a part of the existing data. https://drive.google.com/file/d/1DrQd6kb523wUZDaqhvkx6WBQxJ3wNT3n/view?usp=sharing My data in text …
Names of nodes at depth d for every descendant leaf
I have a category hierarchy that products are attached to. That category hierarchy is saved as an adjacency list. Products can be attached to any category nodes at any level. The category hierarchy is a tree. I would like to… get the name of every level 3 category… per product… where that product is attached to any level 3 category