All Questions
212
questions
0
votes
2
answers
95
views
Left Outer JOIN with no multiple records of left table
A[id, name]
id
name
1001
name1
1002
name2
B[id, productId, serviceId].
id
productId
serviceId
1001
p1
s1
1001
p1
s2
1001
p2
s2
1004
p1
s2
One id in B can have many products & many ...
- 61
-2
votes
1
answer
747
views
I have problem while converting logical model to Relational model in SQL data modeler
I am trying to develop a database for my homework. I designed a Logical Model in SQL data modeler. I tried to convert it to Relational model but Relations were created as Tables. not like relations. I ...
- 11
1
vote
1
answer
665
views
Create and use an index to improve performance
As a follow up to What columns generally make good indexes? where I am attempting to know what columns are good index candidates for my query ?
using ROWNUM for my query, which columns I should add to ...
- 129
0
votes
0
answers
128
views
Database wrapper - Heterogeneous service
Problem
I have 3 databases type Oracle, Mysql, Microsoft SQL. data are the same in all databases.
Is there any way to have 1 database, whatever it is, and store data on it, and have a database ...
- 519
-3
votes
2
answers
128
views
Can we lock on non existing data in Oracle?
Our use case is something similar to this : First we need to check if an active record exists with the given column (non unique), if it does not then create one. Unfortunately duplicate inserts have ...
- 85
1
vote
1
answer
163
views
Sending incremental data to other application from Oracle database:- Even small suggestion would be very helpful
I have 1 table lets suppose Item. there are many DML happens on this table daily. Whatever DML(Insert update delete) happens on this table I need to insert this transaction data into another ...
user14046507
0
votes
1
answer
27
views
How can we get a result from the following tables for a some key values , when the values can change based on user's upload
P1 (Master table) Cols:Teamname TeamID
Data: ABC 1
DEF 2
P2 (Fieldmapping) Cols:FieldDesc Fieldname TeamID:
Data:Goals Text1 1,
...
-1
votes
1
answer
49
views
Structures DB Schema Design
I am working on db schema for the below json. product has different parameterCategories and categories has different parameters. same parameter may belong to different categories. product can have 1 ...
- 57
-1
votes
2
answers
109
views
SQL on Update attribute by joining two table
Let's say I have two tables, and one table is the passenger, and another is the card.
create table passenger(
user_id char(20) not null unique,
name char(20),
age integer,
pin integer,
card_num char(...
- 39
1
vote
1
answer
64
views
add intern in employees table
I have an employees table and the ERD looks like this
I want to add more requirements. I want to add if the employees are seasonal or fulltime. I thought of adding an extra column on the duration ...
0
votes
3
answers
460
views
database design two tables vs join table, which is better
I have two tables matches and tournaments with below structure,
MATCH
MATCH_ID
PLAYER_ID_1
PLAYER_ID_2
RESULT
TOURNAMENT_ID
and
TOURNAMENT
TOURNAMENT_ID
NAME
...
- 5,333
1
vote
1
answer
59
views
Represent levels in a single table or multiple tables
If I have a table with multiple optional levels, is it better to have a single table with nullable levels or multiple tables with not nullable levels.
One benefit I could see is the separate tables ...
- 1,300
-1
votes
1
answer
25
views
Pulling together History data from multiple attribute tables
I have a terribly designed set of database tables that contain data for vessels. The vessel attributes are split up into their own tables (vessel name, length, horsepower, etc). When a vessel is ...
0
votes
2
answers
2k
views
Is it okay for columns with the same name on different tables to have different data types? [closed]
I'm looking for some guidance. Looking through one of our databases we have columns which are all named the same, lets say X. Now column X appears in multiple tables within the same database. However, ...
- 195
1
vote
2
answers
2k
views
How to resolve multiple values in one column in a table?
I have been tasked with designing a database from a scenario. However, while designing my solution I found I would have multiple values in one cell. We were told this is a repeating group and should ...
- 65