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By David on July 21, 2010
Popularity: 4% [?]
By David on May 19, 2010
All the web developer, web admin, as well as DB admin are always facing the attacking from all around the world toward their web site, but how to prevent it?
Some may use the 3th party software to prevent it, some may just filter all the possible keyword enter by the user, some will use the database store procedure to prevent it. The following are some of the keyword that you may need to take care of when you allow your user to enter any input to your system.
Popularity: 4% [?]
By David on August 29, 2009
So, you are now the leader of a SQL Server based project and this is your first one, perhaps migrating from Access. Or maybe you have performance problems with your SQL Server and don’t know what to do next. Or maybe you simply want to know of some design guidelines for solutions using SQL Server and designing Database Access Layers (DAL): this article is for you.
Even if you are not using SQL Server, most of these design guidelines apply to other DBMS, too: Sybase is a very similar environment for the programmer, and Oracle designs may benefit from this too. I won’t show here how to use specific T-SQL tricks, nor won’t give you miracle solutions for your SQL Server problem. This is by no means a complete, closed issue. What I intend to do is give you some advices for a sound design, with lessons learned through the last years of my life, seeing the same design errors being done again and again.
Please, don’t underestimate this tip. This is the best of all of those you’ll see in this article. You’d be surprised of how many SQL Server programmers don’t even know all T-SQL commands and all of those effective tools SQL Server has.
“What? I need to spend a month learning all those SQL commands I’ll never use???” you might say. No, you don’t need to. But spend a weekend at MSDN and browse through all T-SQL commands: the mission here is to learn a lot of what can and what can’t be done. And, in the future, when designing a query, you’ll remember “Hey, there’s this command that does exactly what I need”, and then you’ll refer again to MSDN to see its exact syntax.
In this article I’ll assume that you already know the T-SQL syntax or can find about it on MSDN.
Popularity: 1% [?]
By David on May 27, 2009
I try to google, call, msn my friend to find out the solution when I stay back in my office until late night yesterday. But still no luck after few hours of trying.
Thinking of gave up when back to office this morning, but one of my friend suddently send me the solution via MSN. That’s the best present I received by today. I’m not sure how many people will looking for this kind of solution, but any way, will post here to share with all and you may take it if you need it.
Basically the idea is that you put all your select, update or delete statment into the variable and use the execute command to execute the whole variable.
I have a formula store in a table which is A+B*C+D. My A = 1, B=2, C=3, D=4.
I managed to replace all my variable with the integer using cursor (This maybe not a good solution, but this is not the main discussion in this post)
The finally answer I get is 1+2*3+4. But the bad thing is in the varchar datatype. I only manage to disply 1+2*3+4 but not the answer of 11.
Declare @MathFomula Varchar(100)
Set @MathFormula = ’1+2*3+4′
Exec(‘SELECT ‘ + @MathFormula + ‘ AS Result’
Output: 11
* Remember that * and / will calculate at first before + and -
Popularity: 3% [?]
By David on May 21, 2009
I just found out this usefu function in MSSQL when I try to Google for the solution to replace the null value with something else. So that I no need to do the checking again in my application. The function is call
NULLIF and ISNULL
This 2 functions are actually work opposite with each other.
NULLIF(ColumnName, ValueToCompare) accept 2 parameters, and will return the NULL value if both the expression match.
IFNULL(ColumnName, NewValue) accept 2 parameters, the first parameters is the string that you wish you check with, and the 2nd parameter that you wish to replace with.
Popularity: 3% [?]
