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what exactly is the problem? i.e. what are you trying to acomplish?
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I am not new but somehow I have really avoided getting too involved in database design. My question is fairly basic. If I have a relationship where one object technically possesses many of another, should I just make a standard many to one relation or should I create a bridge table? I will give an example. Let's say that I am trying to keep track of credit card numbers and their owners which I am not just so I don't get screamed at by the security people. The real example would be too hard to explain but this is comparable. So anyways, should I have a credit card numbers table that will have ID (pri key), CCnumber, and Owner columns? Then I would point the Owner column at the pri key column in the People table right? Does it matter that technically that people own credit cards and then maybe I should be making a bridge table? My hunch is that I don't need a bridge table but since this is going to be a big project, I would rather not find out the hard way after I have over 100 tables.
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Using your exampleof people and credit cards, you would have a one-to-many relationship. FYI, it is not called a many-to-one.
You would take the primay key in the people table and include it as a foreign key in the credit card table.
In my experience, you only need a bridge table when you have a many-to-many relationship. A many to many relationship is always broken down to two one-to-many relationships. Consider Students and Courses. A student may take 0,1 or many courses and a course may be taken by 0, 1 or several students. In this case you create an intermediary/relationship/bridge table in which the you have foreign keys from the student and course tables.
I would also advice that you start getting involved in database design
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In your example, a Credit Card can be owned by one and only one person at a time, therefore a bridge table would not be required. A bridge table is required only in a many-to-many relationship.
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I have multiple websites and i am planning to put all on the same web host. All will be storing data on mySQL databases.
My question.... if I want to use the same authentication details (user id and password) for all websites, which way you prefer:
1. Create the same member table in every database related to website, for example in websiteDB1, websiteDB2, etc? so every websiteDB will have membersDB? but technically all memberDB are the same because it's storing the same userIDs and passwords?
2. Create a separate database called memberDB and connect to it from website1 and website2 when the user wants to authenticate?
what's you suggestion?
Thanks,
Jassim
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This depends a lot on the expectations of your users: do they know that the same user name and password let them log in to multiple web sites, or do they expect to be able to change their password on website#1, and keep the old password on website#2? If user name and password must be kept synchronized for all web sites, then there should be only one table; if each web site should have its own pair of user name and password, then obviously there should be multiple tables.
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what about using a separate db for the users profiles but instead of having a single record for the user id and password I'll use multiple records with a flag indicating which service this user id and password belongs to?
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It's a viable alternative, too, but given that you were planning on creating multiple databases anyway, this would seem like an extra maintenance headache. On the other hand, if your database would store little or no site-specific data (i.e. you're creating them almost specifically to support user logins), then using a single database with a flag in a table is definitely a better choice. A lot of this depends on your requirements: once you know what you are trying to achieve, doing the technical side becomes nearly mechanical 
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actually it's different websites including personal site so i thought why should i keep all in one database and the scroll through the tables and stored procedures and ... and....
I am using mySQL and i thought it would be easier to have separate database for every website instead of putting all together or even create a schema because that might end up to large database size?
what do you think?
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If you have different databases for different web sites, and your users would need separate logins to each web site, then keeping the login data with the rest of the site data sounds like a better choice from the design perspective.
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Go with option 2, it sound horrible duplicating user profiles in each db. You could setup tables in your memberDB to control which app each user can login to.
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I am trying to read table data from all my tables in a database to a summary table which contains the table anme in a column, but I am not sure what is the best way to go about doing this. Should I use temp tables or sp_executesql or some other method. I want to use a variable for the table name but I don't think that will work unless I split the string below in 2 and insert a table name. Or should I use temp tables which I am not familiar with or other method, if so how would I do that.
I appreciate any help I can get.
Thanks in advance,
Michael
SET @SQLString1 = N'
DECLARE
@dtLatestDate DATETIME
SELECT @dtLatestDate = B.dtDateTime
FROM
(
SELECT TOP (1) dtDateTime
FROM '
(split here the add tablename, see below)
@TableName
SET @SQLString2 = N'
ORDER BY dtDateTime DESC
) AS B'
OPEN strTableName_cursor;
FETCH NEXT FROM strTableName_cursor INTO @strTableName;
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC sp_executesql @SQLString1 + @TableName + @SQLString2
UPDATE [dbo].[Summary] SET dtLatestDate = @dtLatestDate WHERE strTableName = @strTableName
FETCH NEXT FROM strTableName_cursor INTO @strTableName
END
CLOSE strSymbol_cursor
modified on Saturday, May 14, 2011 3:50 PM
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If you want to vary the table name dynamically then you must use dynamic SQL. There is no alternative.
Either sp_executesql or 'execute' can be used.
Are you sure it needs to be dynamic though?
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Hi All,
I have two tables (sql server)
MainTable
---------
Emp_code BasicPay TotalAddition
------- -------- --------------
160 3000 200
161 4000 100
Additions Table
--------
trx_amount desc emp_code
---------- ---- --------
100 Bonus 160
100 Transport 160
20 Bonus 161
30 Transport 161
50 Food 161
My output grid should be like this
Emp_code Basicpay Bonus transport Food TotalAddition(total of additions)
-------- --------- ------ --------- ------ -------------
160 3000 100 100 0 200
161 4000 20 30 50 100
Please suggest with this
Ramkumar
("When you build bridges you can keep crossing them. ")
http://ramkumarishere.blogspot.com
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You need to pivot[^] the "Additions" table, before joining it to the "MainTable" on emp_code.
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I m a new bee i have used sql server 2000 before my question is when creating two tables in sql server 2000 say
location and projects table projects having a foreign key referencing the location table when inserting values in
location the projects is also updated thats is no need to insert the similar value in the foreign key in projects table
why is it not possible in mysql when i insert values in location using insert command and when using select command on
projects it does not shows the value in foreign key please check the below code
mysql> create table location(
-> id int not null,
-> primary key(id))
-> engine=innodb;
Query OK, 0 rows affected (0.11 sec)
mysql> create table projects(
-> id int,
-> location_id int,
-> foreign key(location_id) references location(id) on update cascade on del
ete cascade)
-> engine=innodb;
Query OK, 0 rows affected (0.31 sec)
mysql> insert into location values('1')
Query OK, 1 row affected (0.34 sec)
mysql> select * from location;
+----+
| id |
+----+
| 1 |
+----+
1 row in set (0.00 sec)
mysql> select * from projects;
Empty set (0.00 sec)
as u see in the above code it was possible in sql server 2000 that the value was reflected in the child table why is
it not possible in MySql Why should the value be insert in both the tables isn't it possible in MySql that when i insert
in the location table the projects table pick the value automatically and show it in select Query when i query the projects table
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Do not create duplicate posts, you can edit your previous post and make your additions.
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I m a new bee in mysql i have used sql server 2000 before my question is when creating two tables in sql server 2000 say location and projects table projects having a foreign key referencing the location table when inserting values in location the projects is also updated thats is no need to insert the similar value in the foreign key in projects table why is it not possible in mysql when i insert values in location using insert command and when using select command on projects it does not shows the value in foreign key why should the value be insert in both the tables isn't it possible that when i insert in the location table the projects table pick the value automatically and show it in select result when i query the projects table
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There is nothing it TSQL (Microsoft SQL Server "Transactional SQL") that is going to automatically insert foreign key values.
You might have used some tool that created TSQL for you, but then it generated TSQL which explicitly inserted the key value.
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Hi there,
i have a sql server table there i have thousands of record and when i call it from Stored procedure then it will take very huge time to display records how can i make Fast.
Thanks in Advance
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Returning thousands of rows is usually not the problem.
The problem is usually in the query (your stored procedure).
It might help if you were to post the Stored Procedure?
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Without your query I can only suggest things to try as I had to do something similar just recently
1. Break your query down into sections and find what part is slow
2. Indexing your data.
or like the other poster suggested, post your query
Nagy Vilmos wrote: And eat bacon. Bacon's real important for 'puters.
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The general answer is write more efficient code. Since you haven't posted your code, we can't tell you where to improve it.
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In general you shouldn't be attempting to display "thousands" of records in the first place.
This typically occurs in list box type displays for users who are interested in looking at the records. But those users don't want 'thousands" what they want is a very small subset very likely one record. And they know what they are looking for. So only display the single record they are looking for.
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Posting your query will help us determine your problem, but here are some general tips:
1. Index your table(s) properly.
2. Select only the required rows using a properly constructed WHERE clause.
3. Select only the required columns.
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