I have tried everything i thought would work for this and am turning up nothing. in rails 3, I need to find all users with a cd player in their car. A car has one user and one radio, and a user belongs to a car, and a radio has many cars. I am stumbling on how I would perform
Calculating difference between two timestamps in Oracle in milliseconds
How do I calculate the time difference in milliseconds between two timestamps in Oracle?
Selecting from two non-related tables at the same time
Suppose I have a table with lots of rows and columns (alias: bigtable), and a table that always has 1 row, but multiple columns (alias: 1rowtable). The 1rowtable has nothing to do with bigtable, it is …
Differences between PostgreSQL and MySQL for PHP developers
For a project where most queries on the database will include requirements like “within an polygon” I have come to think about choosing PostgreSQL with PostGIS instead of MySQL, which I have previously mainly used. Mainly because PostgreSQL has more GIS functions. However, I am uncertain how to ev…
How to simulate a deadlock in SQL Server in a single process?
Our client side code detects deadlocks, waits for an interval, then retries the request up to 5 times. The retry logic detects the deadlocks based on the error number 1205. My goal is to test both the deadlock retry logic and deadlock handling inside of various stored procedures. I can create a deadlock using…
SQL Server database backup file (.bak ) file gets corrupted
I have been working on a SQL Server database designing since long now and I have observed that when a .bak file is mailed or kept and downloaded from ftp site, it gets corrupted. When I try to restore, it gives me 3013 error code with messsage: “Backup or restore operation terminating abnormally. I trie…
How to return default value from SQL query
Is there any easy way to return single scalar or default value if query doesn’t return any row? At this moment I have something like this code example: How to do that in better way without using IF-ELSE? Answer Assuming the name is not nullable and that Id is unique so can match at most one row.
NULL values are excluded. Why?
This is about a bizarre behaviour I found in Microsoft Sql Server. Please correct me if I’m wrong. SELECT COUNT(*) FROM TABLEA WHERE [Column1] IS NULL; This returns 30018 rows. CREATE VIEW VIEWB …
How to join the same table twice?
I am stuck on creating a SQL query. I have the following two tables: sender and receiver are foreign keys with table member and column memberid. I want to display list of messages with name and id of sender and receiver. How can I establish proper joins here? Answer You can try something like
how to bind dropdown list in a gridview from database and also edit and update it
I want to bind dropdown list in a gridview with datasiursce coming from data base, and i also want to edit and update it if required. The datasource contains the data i want to fetch,its doesnt bind …