Database

15-Jun-07 1:15

You've already posted this question - just below in fact. Please don't repost.

Deja View - the feeling that you've seen this post before.

Re: mysql exchange data

Colin Angus Mackay15-Jun-07 4:13

15-Jun-07 4:13

Pete O`Hanlon wrote:
You've already posted this question - just below in fact. Please don't repost

Actually, the post below was orginally asking if it was okay to post a question on MySQL in this forum. When I replied that it was okay he then changed the content of the post to the question he wanted to ask.

Upcoming events:
* Glasgow: Mock Objects, SQL Server CLR Integration, Reporting Services, db4o, Dependency Injection with Spring ...
* Reading: Developer Day 5

Never write for other people. Write for yourself, because you have a passion for it. -- Marc Clifton

My website

Re: mysql exchange data

Pete O'Hanlon15-Jun-07 4:31

15-Jun-07 4:31

Hmmmm. Oh well - still breaching the "rules" though. Big Grin | :-D

Deja View - the feeling that you've seen this post before.

permission [modified]

p_14-Jun-07 23:40

14-Jun-07 23:40

thanks sir
hi all
sir i have made a database and a table and add data in tables in mysql

but then i reinstall another version of mysql .
now i cut the data folder from older version and paste it
into newer version
now when i use show databases in newer version of mysql
it will show that database and tables also
but when i try to show values in tables it will give an error that this table
does not exists
please sir

thanks Rose | [Rose]

-- modified at 6:04 Friday 15th June, 2007

Re: permission

Colin Angus Mackay14-Jun-07 23:49

14-Jun-07 23:49

paras_s12 wrote:
can i ask a query related to mysql please in this section

Yes

Re: permission

Colin Angus Mackay14-Jun-07 23:57

14-Jun-07 23:57

I should add that unless your question relates to the way MySQL interacts with .NET applications you may find the responses limited. If it is a purely MySQL question then a forum that deals with that would more likely be useful to you. People will still be able to help you, there are just less of them specialised in that technology here.

Welcome anyway. Big Grin | :-D

Two fields can't repeat

N a v a n e e t h14-Jun-07 22:54

14-Jun-07 22:54

Assume that I have a table with UserName and Password columns. Both are varchar type. I given primary key for UserName. But we got another requirement that Password also should not repeat. So I tried setting primary key for Password also. But my first attempt resulted in failure. SQL said you can't create multiple primary keys on a table. Is there a concept called composite key ? Is it related to my requirement ? Or is there any other way to make both fields to be acted like primary key (Both fields should not repeat).? Confused | :confused:

Navaneeth
My Website

Colin Angus Mackay14-Jun-07 23:05

14-Jun-07 23:05

You can mark a column as UNIQUE which ensures its value doesn't repeat. However, I don't believe that fits your requirements.

What if two independent users happen, by chance, to pick the same password? What if one of them is mallicious? The fact the second user cannot choose their password means they know someone else already has that password. Now their brute force attack on the system is faster because they have a known password and just have to match it to an existing user.

Most systems don't allow a user to duplicate a password they've used in the past. I would guess that it your requirement. In which case you need to store a history of passwords for each user.

N a v a n e e t h14-Jun-07 23:14

14-Jun-07 23:14

Colin Angus Mackay wrote:
What if two independent users happen, by chance, to pick the same password?

Thanks, But this is not the real scenario. I just given a simple example about my requirement. I am using this in another table. Not using for users. Any other way to ensure both of the fields won't repeat ?

Navaneeth
My Website

Christian Graus14-Jun-07 23:30

Christian Graus

14-Jun-07 23:30

What he told you to do, solves the problem. He was just telling you why not to do it with passwords.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Colin Angus Mackay14-Jun-07 23:54

14-Jun-07 23:54

Navaneeth. wrote:
Thanks, But this is not the real scenario

Why not tell us the real scenario? It would have mean I didn't have to write all those warnings about security which are, only now, obviously not needed.

Sometimes I really wonder whether I'm wasting my time helping here or not.

N a v a n e e t h15-Jun-07 1:12

15-Jun-07 1:12

Real scenario is, I store ItemCode and ItemName in one table. ItemCode is primary key. I don't want to repeat ItemName also. For that I tried this. Actually I just given a example about username and password to understand the problem easily. But I think I am mistaken and my first example made lot of confusion. Sorry.

Colin Angus Mackay wrote:
Sometimes I really wonder whether I'm wasting my time helping here or not.

Never. Your postings are excellent. You are doing good job. Thanks

Navaneeth
My Website

Arun.Immanuel15-Jun-07 1:19

Arun.Immanuel

15-Jun-07 1:19

Colin Angus Mackay wrote:
Sometimes I really wonder whether I'm wasting my time helping here or not.

Not only the poster whom you are replying gets benefited.
It helps everyone who sees you reply.

Colin Angus Mackay wrote:
I didn't have to write all those warnings about security

These warning may help others.;)

So you are not wasting you time.

Regards,
Arun Kumar.A

Pete O'Hanlon14-Jun-07 23:05

14-Jun-07 23:05

Instead of creating a single primary key per field, you can select all of the fields that you want and create it as a primary key in one go.

Deja View - the feeling that you've seen this post before.

N a v a n e e t h14-Jun-07 23:15

14-Jun-07 23:15

Thanks, I tried that SQL Server created all the selected fields as primary. But still it is checking only the last field. Remaining all fields in the primary list are allowing repeats. Any other alternative for this ?

Navaneeth
My Website

Colin Angus Mackay14-Jun-07 23:52

14-Jun-07 23:52

The primary key as a whole will be unique. Individual elements within the primary key may not be unique.

Pete O'Hanlon15-Jun-07 0:26

15-Jun-07 0:26

If the fields must be unique, then you need to implement a unique index on each field that you want to be unique, e.g.

CREATE UNIQUE 
  INDEX [] ON [dbo].[Workspace] ([Description])

Deja View - the feeling that you've seen this post before.

mysql

WhiteGirl2314-Jun-07 22:48

WhiteGirl23

14-Jun-07 22:48

Hi,
I work on a project which transfer an access database in mysql.

My problem is that I have a function which convert a binary information in mysql and that function doesn't work so good. This function looks like this:

While i <= Len(str)<br />
<br />
                Select Case Mid$(str, i, 1)<br />
<br />
                    Case Chr(0)  ' ASCII NUL<br />
                        'nlstr = ""<br />
                        rstr = "\0"<br />
<br />
                    Case Chr(8)  ' backspace<br />
                        'nlstr = ""<br />
                        rstr = "\b"<br />
<br />
                    Case Chr(9)  ' tab<br />
                        'nlstr = ""<br />
                        rstr = "\t"<br />
<br />
                    Case Chr(180)<br />
                        'nlstr = ""<br />
                        rstr = " '' "<br />
<br />
                    Case "'"<br />
                        'nlstr = ""<br />
                        rstr = "\'"<br />
<br />
                    Case """"<br />
                        'nlstr = ""<br />
                        rstr = "\"""<br />
<br />
                    Case "\"<br />
                        'nlstr = ""<br />
                        rstr = "\\"<br />
<br />
                    Case Chr(10)  ' line feed<br />
                        'nlstr = ""<br />
                        rstr = "\n"<br />
<br />
                    Case Chr(13)  ' carriage return<br />
                        'nlstr = ""<br />
                        rstr = "\r"<br />
<br />
                End Select<br />
<br />
                If rstr <> "" Then<br />
                    str = Left$(str, i - 1) & rstr & Right$(str, Len(str) - i)<br />
                    i = i + Len(rstr)<br />
                    rstr = ""<br />
                Else<br />
                    i = i + 1<br />
                End If<br />
<br />
            End While<br />
<br />

where str is the information.

If you have an idea please help me.

Thanks.

Re: mysql

N a v a n e e t h14-Jun-07 23:04