Tagged Questions

2
votes
5answers
531 views

Does 'Cities' deserve a separate table?

I have the following Customers table: customer_id - int company_name - nvarchar street - nvarchar city - nvarchar comments - nvarchar The app will only be used in part of one small country ...
0
votes
3answers
161 views

Is adding rows better then adding columns in case their value is not consistent?

In my project I have a table of customers, each customer has his own special price for each product, It's a small business and there are currently about 5 products. The manager says there might be ...
2
votes
2answers
104 views

Long JOINS Returns No result all tables have one to many relationship with a particular table [closed]

I have a Table Enterpries with Primary Key 'RCNO'. All other tables have a one to many relationship with Enterprise via it's RCNO column. I make a Join of all the tables and i get nothing. Below is ...
2
votes
1answer
85 views

Group_by and having vs Joins when table is self joined 5-6 times

Now the situation due to which this question came to me. Schema is Table User_Read_Book user_id | book_id Now I want to get users who have read certain books. Say give me users who ...
2
votes
2answers
202 views

Joining based on date (or date range)

I'm not sure if I've completely fudged the design of my small hobby database (I'm not a DBA by any means), but I have a table like this (primary key is (staffid, effectivefrom)): staffid | target | ...
2
votes
3answers
230 views

Express union which is dependent on other results

I would like to make a union of two tables that are actually in a hierarchical constellation. How would I write that in relational algebra? Say table A is the parent of B in a 1:n relationship. ...
10
votes
3answers
1k views

Column name naming conventions and best practices

I would like some expert opinion on best practices when it comes to column naming. The background is that according to Wikipedia, the following syntax, SELECT ... FROM Employees JOIN Timesheets ...
5
votes
5answers
11k views

Matching single column against multiple values without self-joining table in MySQL

We have a table that we use to store answers to questions. We need to be able to find users that have certain answers to particular questions. So, if our table consists of the following data: user_id ...