Oracle Multiple schemas Vs single schemas - Database Discussion Boards

SQL Server Authentication issue - Fixed, but I don't understand why

gantww3-Mar-11 5:55

3-Mar-11 5:55

Greetings,
I've been having an issue on one of our servers here where we could not connect to the SQL database hosted on the same machine over named pipes from a web application. We could, however, connect from enterprise manager using the same credentials. Shutting the firewall off didn't help, nor did any tweak we made to the sql server configuration. While biting my lip in despair, I happened to notice that the system time was off by three years. I figured I'd fix it while I was trying to figure out what to do with SQL. Once I fixed it though, SQL authentication started working again.

Now, while I'm totally stoked that I was able to fix the problem, I don't understand WHY that fixed the problem, and I do try to avoid cargo-cult style system repairs. Can anybody explain this to me?

Thanks,
Will

complicated select

benams3-Mar-11 5:16

benams

3-Mar-11 5:16

I'm not familiar enough with SQL syntax, and I need to make a little complicated SELECT.
I have a table with 3 fields: contentID, date and readsCounter.
I have to get the top 2 read contents for the last 2 days.
For example:

contentID: 0, date: 1-1-2000, readsCounter: 10
contentID: 0, date: 2-1-2000, readsCounter: 80
contentID: 1, date: 1-1-2000, readsCounter: 40
contentID: 1, date: 2-1-2000, readsCounter: 5
contentID: 2, date: 1-1-2000, readsCounter: 20
contentID: 2, date: 2-1-2000, readsCounter: 30

the lines above are 6 records from my db, contents 0 and 2 are the contents that need to be selected(the contents and the reads sum for the last 2 days).
I'm working with MSACCESS DB. someone can help me?

Re: complicated select

Chris Meech3-Mar-11 8:45

Chris Meech

3-Mar-11 8:45

The dates are from 10 years ago, so how would they be considered for the last 2 days. Confused | :confused:

Chris Meech
I am Canadian. [heard in a local bar]

In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]

posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

Re: complicated select

Jörgen Andersson3-Mar-11 9:37

Jörgen Andersson

3-Mar-11 9:37

Maybe it's an old book.

List of common misconceptions

Re: complicated select

Mycroft Holmes3-Mar-11 13:52

Mycroft Holmes

3-Mar-11 13:52

Use a combination of Row_Number and Partition. You need to create a 2 query select, the first injects the row_number based on the partition of contentid and date, ordered by readscounter.

The outer query selects anything with a row_number < 3.

Never underestimate the power of human stupidity
RAH

Re: complicated select

benams4-Mar-11 7:35

benams

4-Mar-11 7:35

can you add an example code for what you have suggested? I'm afraid I don't completely understand how to implement this.

Re: complicated select

Mycroft Holmes4-Mar-11 12:49

Mycroft Holmes

4-Mar-11 12:49

Then I found a simpler way when I actually worked the query.

SELECT TOP 2
  contentID,
  RC  
FROM
  (SELECT
    contentID,
    SUM(readsCounter) RC
   FROM
    Book1 AS B
   --WHERE ReadDate BETWEEN this AND that
   GROUP BY
    contentID) D
ORDER BY RC desc

Note the where clause will be required when the data set is larger

Never underestimate the power of human stupidity
RAH

Oracle Multiple schemas Vs single schemas

V.2-Mar-11 20:11

2-Mar-11 20:11

We're building a new system (consisting of multiple applications) from scratch and use Oracle as a database.
The problem is that we don't know how big it will grow and what new decisions (from managers) we will have to go through in the future.

My opinion is that we just use one schema to start out with and see where we get from there. My colleague (coming from SQL-Server background) opted the idea to use multiple schemas. One for each different application in the system plus a config and common (=for all applications) schema. His main reason being security.
(But what if a table that starts belonging to one application later needs to be shared among applications?)

Another option would be to seperate tablespaces, but use the same schema.

I'm not sure what the best design is (and I'm no Oracle expert either). We don't know were we'll go with this system, it might grow internationally, it might die next year. My experience tells me that you should design very well, but without overkill.

Do you have experience with designing databases and what is your take on this? (Pro's/Con's). Google does have some examples, but mostly they are when different companies need to access the same database. This is not our case.

Many thanks in advance.

Re: Oracle Multiple schemas Vs single schemas

Jörgen Andersson2-Mar-11 21:08

Jörgen Andersson

2-Mar-11 21:08

V. wrote:
His main reason being security.

Good reason.

V. wrote:
But what if a table that starts belonging to one application later needs to be
shared among applications?)

Then you have to set the access rights accordingly and add the schema to the tablename when accessing it.
Like this: Select * from schemaname.tablename

V. wrote:
Another option would be to seperate tablespaces, but use the same
schema.

Thats something completely different. That's a logical storage space[^].

List of common misconceptions

Re: Oracle Multiple schemas Vs single schemas

Mycroft Holmes2-Mar-11 22:17

Mycroft Holmes

2-Mar-11 22:17

I'm pretty sure tablespaces have nothing to do with your segregation of data, it is only for logical storage.

We have just run across a real need for additional schemas, we want to move the production data (ETLd from other systems) to the dev server, if the data was in different schemas this would be simple, now we have to reengineer the database schemas to meet that requirement.

Security is another issue so I would go for the additional schemas from the start. As for moving from 1 schema to anoter I believe there are tools to help (Toad) and it is just the price you pay for getting it wrong (or changing requirements).

Never underestimate the power of human stupidity
RAH

Re: Oracle Multiple schemas Vs single schemas

PIEBALDconsult3-Mar-11 1:56

PIEBALDconsult

3-Mar-11 1:56

The only place I worked with Oracle we had one big happy database and it was fine. Keep it simple.

Re: Oracle Multiple schemas Vs single schemas

Wendelius4-Mar-11 10:28

Wendelius

4-Mar-11 10:28

Hi,

Somekind of list of thoughts on this issue:
- security is a good point. Although security can be enforced on many different levels you can use owner permissions for example in packages. This helps to handle common security problems.
- logical design. If you separate the objects to different schemas based on the data they hold, it's easier to understand the database design (and usage) especially in bigger databases.
- backups and other DDL operations. Many of the operations can be done schema based. For example you can export a certain schema so this helps in administrative tasks
- usage in applications. This is two folded, you can either define the schema in applications (like SELECT ... FROM schema.table) or you can use public synonyms to hide the structure. Public synonyms are bad in situations where you actually need for example a table with the same name twice in the database but otherwise they should simplify the use in the apps.
- isolation. Using different schemas you can isolate different portions of the database more easily (a bit same as the security) but again this can be done in multiple ways.

V. wrote:
Another option would be to seperate tablespaces, but use the same schema

This is a totally different issue. Tablespace is used to define the actual storage place for an object regardless of the schema. A simple situation is that you have a table and an index on it. In optimal case they are stored on different disks so they would be stored on different tablespaces even though they both would be defined in the same schema. So tablespace is just a way to define physical storage place without defining the actual file (since tablespace can contain multiple files).

The need to optimize rises from a bad design.My articles[^]

Re: Oracle Multiple schemas Vs single schemas

V.4-Mar-11 10:48

4-Mar-11 10:48

This is in fact what we did finally. Created schema per application and a common one holding configuration data and parameters etc. For that schema we made public synonyms.

After everything was moved I had to change very little to my prototypes to make them work Smile | :)

thanks for the advice.

Re: Oracle Multiple schemas Vs single schemas

Wendelius4-Mar-11 10:54

Wendelius

4-Mar-11 10:54

No problem Smile | :)

The need to optimize rises from a bad design.My articles[^]

How to write a SQL query to present values horizontally sql server 2005

Tridip Bhattacharjee1-Mar-11 20:10

Tridip Bhattacharjee

1-Mar-11 20:10

Suppose I have one table called Jobs:

CREATE TABLE [Jobs]
(
[JOBID] [int] IDENTITY(1,1) NOT NULL,
[PARTDESC] [nvarchar](64) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[OrderPlacedBy] [nvarchar](64) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[SpecialistName] [nvarchar](64) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[Priority] [int] NOT NULL,
[Symptoms] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[CustomerNotes] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[ShopNotes] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[JobType] [nvarchar](32) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
[JobState] [nvarchar](32) COLLATE Latin1_General_CI_AS NULL,
[JobAddedDate] [datetime] NOT NULL,
[JobStartedDate] [datetime] NULL,
[JobFinishedDate] [datetime] NULL,
[JobShippedDate] [datetime] NULL,
[RecievedDate] [datetime] NULL
)

I want to see the specialist name and his jobs IDs horizontally.

ANA 201,502,605,701,774
BEN 102,103,051
JEN 705,401,402,509,409,408

A specialist may have n jobs. Suppose specialist ANA has 10 jobs where BEN has 5 jobs.

In this way I want to show specialist his jobs horizontally where the number of jobs may vary per specialist.

How can I do this in SQL?

tbhattacharjee

Re: How to write a SQL query to present values horizontally sql server 2005

Jörgen Andersson1-Mar-11 20:27

Jörgen Andersson

1-Mar-11 20:27

Make a search on Pivot[^].

List of common misconceptions

Re: How to write a SQL query to present values horizontally sql server 2005

Mycroft Holmes1-Mar-11 21:49

Mycroft Holmes

1-Mar-11 21:49

There are some excellent articles [^]here on CP (blatant self promotion here)

Never underestimate the power of human stupidity
RAH

Re: How to write a SQL query to present values horizontally sql server 2005

Wendelius4-Mar-11 10:37

Wendelius

4-Mar-11 10:37

Must say that you found an excellent article for this issue ! Smile | :)

The need to optimize rises from a bad design.My articles[^]

Re: How to write a SQL query to present values horizontally sql server 2005

PIEBALDconsult2-Mar-11 2:18

PIEBALDconsult

2-Mar-11 2:18

With Sql Server, you can write your own aggregate function[^].

And you spelled received wrong.

database design

wjbjnr1-Mar-11 9:27

wjbjnr

1-Mar-11 9:27

i am recently new to database designs..i have been working on samples but never designed a sql database...please help with a tutorial or recommend a book so that i can design a database and use linq in c# to access it...by designing a database .simply meaning creating plain tables and manipulating data in it..i have sql server management studio 2008 and have visual studio 2010 ultimate also...please guide towards a simple and easy way to get started..

Re: database design

Mycroft Holmes1-Mar-11 21:52

Mycroft Holmes

1-Mar-11 21:52

You have asked one huge question. Try doing some research.

Heres some Google foo[^] for you

Then try a C# tutoral and a Linq tutorial. You have the word you just need to do the research.

Never underestimate the power of human stupidity
RAH

Re: database design

thatraja2-Mar-11 12:32

thatraja

2-Mar-11 12:32

Also this will help you, start with this.

Library of Free Data Models from DatabaseAnswers.org[^]

thatraja

My Tip/Tricks
My Dad had a Heart Attack on this day so don't...

Re: database design

V.2-Mar-11 20:14

2-Mar-11 20:14

If you have the budget, hire a senior consultant that will explain you in-depth (teach you) the workings of SQL-Server. I had a two day Oracle session not long ago and it gave me some insight into do's/don'ts. It remains difficult to design it still, but it will give you more confidence in what you're about to get yourself into.

Re: database design

Wendelius4-Mar-11 10:34

Wendelius

4-Mar-11 10:34

It's good that you have excellent tools to administer the database but in order to use the tools correctly you must understand what happens "under the hood", so one of the "must have" books is: http://www.amazon.com/Introduction-Database-Systems-8th/dp/0321197844[^]

Also see the section "Customers Who Bought This Item Also Bought..."

The need to optimize rises from a bad design.My articles[^]

Can't get my query to work on a form!

venomation1-Mar-11 3:06

venomation

1-Mar-11 3:06

I am not very good at Microsoft Access's queries, they seem different than standard SQL.
I have the following query:

SELECT COUNT(*) AS Total
FROM CDCopy
WHERE CatalogueNumber=[Please enter the catalogue number to find out how many copies are available];

If I double click the query it shows an input box and the rest works as intended.

The problem is that I don't know how to use it in a form!
I have tried :

MsgBox([GETCDCopyCount]![Total]![CatalogueNumber])

Where "[CatalogueNumber]" is a textbox as I want to pass the text information from that box into the query.

Keep getting error messages, can someone help me out? Big Grin | :-D

Thanks!

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