A trigger is a stored procedure that automatically executes when an event occurs in the database server.Triggers execute when users try to modify something or behind an event that generate changes on the data base.There are three kind of triggers: for insert , update , and delete.The most important events correspond to Transact-SQL CREATE, ALTER, and DROP statements, and certain system stored procedures that perform DDL-like(data definition language) operations.Triggers can be created in the SQL Server 2005 Database Engine directly from Transact-SQL statements or from methods of assemblies that are created in the Microsoft .NET Framework common language runtime (CLR) and uploaded to an instance of SQL Server.Using SQL Server you can create lots of triggers for any specific statement.

Syntax:

CREATE TRIGGER trigger_nameON { ALL SERVER | DATABASE }

[ WITH <ddl_trigger_option> [ ,...n ] ]

{ FOR | AFTER } { event_type | event_group } [ ,...n ]
AS { sql_statement  [ ; ] [ ,...n ] | EXTERNAL NAME

< method specifier >  [ ; ] }<ddl_trigger_option> ::=

[ ENCRYPTION ]

[ EXECUTE AS Clause ]

<method_specifier> ::=

assembly_name.class_name.method_name

schema_name

Is the name of the schema to which a DML trigger belongs. DML triggers are scoped to the schema of the table or view on which they are created. schema_name cannot be specified for DDL or logon triggers.

trigger_name

Trigger name is the name of the trigger. Is not allowed to start the trigger name with # or ##.

table/view

Table or view are the table or view where trigger is executing on.Triggers cannot be defined on local or global temporary tables.

DATABASE

Current data base where changes are making on.

ALL SERVER

Is the current server where are the tables or views that we make changes.If specified, the trigger fires whenever event_type or event_group occurs anywhere in the current server.

WITH ENCRYPTION

Using WITH ENCRYPTION prevents the trigger from being published as part of SQL Server replication.

EXECUTE AS

Specifies the way is executed the trigger.This way users validate permissions on any database objects that are referenced by the trigger.

FOR | AFTER

After - means that trigger can be executed only after all operations specified in the triggering SQL statement have executed successfully.

event_type

Is the type of event that release the trigger for executing.

sql_statement

Is the trigger conditions and actions. Trigger conditions specify additional criteria that determine whether the tried DML, DDL, or logon events cause the trigger actions to be performed.The trigger actions specified in the Transact-SQL statements go into effect when the operation is tried.

method_specifier

The method must take no arguments and return void. class_name must be a valid SQL Server identifier and must exist as a class in the assembly with assembly visibility. If the class has a namespace-qualified name that uses ‘.’ to separate namespace parts, the class name must be delimited by using [ ] or ” ” delimiters. The class cannot be a nested class.

We have a mysql table that stores all orders of an online store. Each order has off course a field that represents the status of this order. That can be ‘pending’, ‘payment_received’, ‘approved’, ’shipped’, ‘completed’ .

Those statuses are found in the majority off good online stores so this is a practical theory.

Now what if we want to list all orders, but sorted like 1st the ‘pending’ ones, 2nd the ‘payment_received’ ones, 3rd the ‘approved’ one 4th the shipped ones and last the ‘completed’. Off curse if you think of it from the beginning you’ll probably structure your table such way so that is wasy to be done by a simple sort by . But what if your application is already done and you just need to add this small thing?

Well mysql can save from a ton of work . You can use advanced decision statements on the group by. We’ll just use a switch type of statement and we’ll basicly assign each value of the status a numeric value and we’ll sort on that.

Here is how the order by clause would look like :

ORDER BY

CASE order_status

      WHEN 'pending'   THEN 1

      WHEN 'payment_received'   THEN 2

      WHEN 'approved' THEN 3

      WHEN 'shipped'   THEN 4

      WHEN 'completed' THEN 5

      ELSE 99999

END

The above will do exactly what we want. Will test the values of order_status field and will assign to that a numerical value used jst for search. Such a nice thing that does your life much easier when you really need it…

In this article, I will show you how to setup a development environment using Perl and SQL Server on the following platforms: Microsoft Windows, Red Hat Linux, and Sun Solaris. Step by step, you can learn, and may choose, the best way that fits into your own requirements.

SQL Server was a product that originated from Sybase Inc., and became a popular DBMS product on the market from the end of 1980s. In the early days Sybase SQL Server was running on the UNIX platform while PCs still used MS DOS (single task OS) – an operating system which was not suitable to develop and run a DBMS.

In 1987, Sybase and Microsoft signed a contract on joint development to port SQL Server to OS/2 (Multi-task OS) which became the replacement for MS DOS (OS/2 owned by both IBM and Microsoft). The OS/2 project did not continue for long, and Microsoft decided to develop its own multi-task operating system (Windows) and stop its contract with IBM. In 1990, with the successful release of Windows 3.0, Microsoft also released its Windows version of SQL Server – Microsoft SQL Server.

Milestones for MS SQL Server:

• MS SQL Server 4.2 (16-bits, Jan. 1992)
• MS SQL Server for Windows NT (32-bits, July, 1993)
• MS SQL Server 6.0 (June, 1995)
• MS SQL Server 6.5 (April, 1996)
• MS SQL Sever 7.0 (Nov. 1998)
• MS SQL Server 2000 (Aug. 2000)

At the same time, Sybase dominated the Unix DBMS market. From Sybase SQL Server 4.2 (released around 1989, introduced unions), Version 4.8 (1990, introduced multiprocessor architecture), Version 4.9 (1992, more stable product, support SMP) Version 10 (1993, introduced server-side cursor, auditing and backup server), Version 11, Sybase Adaptive Server 12, until today: Sybase Adaptive Server 12.5.

Although in 1994, Microsoft and Sybase announced the end of the contract on joint SQL Server Development, MS SQL Server 6.5 and Sybase SQL Server 10 and all their previous versions used the same core code and were easily able to access each other.

MS SQL Server 7.0 changed completely from its previous version and was no longer compatible with Sybase SQL Server. But, with the release of Service Pack 2 for SQL Server 7.0 (Microsoft Knowledge Base Article – 239883 “Fix: SYBASE CT-Library Clients Cannot Connect to Microsoft SQL Server 7.0”) we had one last chance to access MS SQL Server 7.0 from the Sybase Client (Sybase SQL Server was more compatible with MS SQL Server, as you could successfully access Sybase SQL Server from the MS SQL Server 2000 client, iSQL).

Executing SQL Server Stored Procedure from Perl - TDS protocol

SQL Server uses a typical Client-Server architecture. The SQL Server client is a set of C APIs plus management tools such as iSQL query tool and SQL Server Enterprise Manager. SQL Server Server-Side component is usually a system service, listening to specific TCP ports (Microsoft use 1433, Sybase use 4100 or 5000), and is ready to accept the signal from an SQL Server client at anytime.

The protocol used between an SQL Server client and server is traditionally called the TDS protocol (Tabular Data Stream). Microsoft SQL Server 4.2, 6.0, and 6.5 use the same TDS protocol as Sybase SQL Server 4.2 and 10, which is known as TDS4.2.

From Version 11, Sybase stopped further development of the old set of APIs (we call DB-Library) and started a new set of APIs, known as CT-library. They also redesigned the TDS protocol, which is now known, industry-wide, as TDS 5.0. At the same time, Microsoft chose to stick to DB-Library but enhanced the TDS protocol, which we call TDS 7.0. But, do not think that TDS 7.0 is more advanced than TDS 5.0 or compatible with TDS 5.0. In fact, TDS 7.0 belongs solely to Microsoft SQL Server (we’re better off to call it Microsoft TDS) and TDS 5.0 belongs specifically to Sybase (Sybase TDS).

So, we easily understand that the latest version of Microsoft SQL Server (2000) supports TDS 7.0 and TDS 4.2 (backwards compatibility) and Sybase SQL Server’s latest version 12.5 supports TDS 5.0 and TDS 4.2 (backwards compatibility).

Executing SQL Server Stored Procedure from Perl - Setup Perl and SQL Server on Windows

Perl’s running environment is integrated within the *nix system. For Microsoft Windows operating systems, however, you need to download and install it by yourself.

There are a few Windows-based distributions of Perl. ActivePerl from ActiveState.com may be the most popular one. You can download it from:

http://www.activestate.com/Products/ActivePerl/

Choose the latest version of ActivePerl (5.8) (most recent Unix/Linux also uses Perl 5.8).

Installing ActivePerl on Windows is fairly easy. After installation you can use the following command to verify that perl is working:

From command prompt, input:

Perl –v

It will show you something like:

This is perl, v5.8.0 built for MSWin32-x86-multi-thread
Copyright 1987-2002, Larry Wall

Download Sybase Adaptive Server 12.5 Developer Edition from the Sybase website for free: www.sybase.com/ase_125devel

Installing and configuring Sybase Adaptive Server is also as easy as MS SQL Server.

If you want to use MS SQL Server as a database, install MS SQL Server 7.0 with service pack 2.

Perl uses DBI/DBD architecture to access databases (DBI means Database Interface, DBD means Database Driver). With a specific DBD driver installed, Perl can use the same DBI API to support different database systems.

The DBI module is already installed with the ActivePerl distribution itself. In order to support SQL Server, we need to download the SQL Server DBD driver from cpan.org: www.cpan.org, search for the DBD-Sybase module, and download the latest version 1.01 source code: DBD-Sybase-1.01.tar.gz

Note: there are a few other DBD Drivers that support both Sybase and Microsoft SQL Server on Windows, such as DBD::ADO; however, they can only be used on a Windows platform.

In order to compile and install the DBD::Sybase source code, we need a C compiler installed on Windows (I use Microsoft Visual C++ 6.0), and make sure nmake.exe is available in the PATH.

Use a decompression utility (ie: Winzip) to extract DBD-Sybase-1.0.1.tar.gz to any available drive such as C:. You should now have the folder c:DBD-Sybase-1.01 that holds all the source code.

Change directory to the above folder, and issue the following command in the command prompt window:

Perl Makefile.PL

You may receive a warning message, such as missing the following library: libtcl.lib, libcomn.lib and libintl.lib.

Because we are using the Sybase CT-Library, libcs.lib and libct.lib are mandatory; others are optional, and we can ignore this warning. Sybase removes these static libraries from its version 12.5 of the Adaptive Server package. The run time libraries still do exist (ie: libtcl.dll, libcomn.dll, linintl.dll)

If you receive an error message other than the one above, please check the following environment variable: SYBASE and SYBASE_OCS
%SYBASE% should equal the directory root where Sybase Adaptive Server is installed (ie: C:sybase) and %SYBASE_OCS% should equal OCS-12_5 for Sybase Adaptive Server 12.5

Issue the following command to compile the source code:

Nmake

Then install the package by issuing this command:

Nmake install

Using the following code, we can list all the DBD drivers we’ve installed with Perl:

#!/usr/bin/perl

use strict;
use DBI;
my @drivers=DBI->available_drivers();
print join(”n”,@drivers);
print “n”;

Copy and paste the above code in notepad, and save the file as dbi_drivers.pl.

Issue the following command in the command prompt window:

perl dbi_drivers.pl

Executing SQL Server Stored Procedure from Perl - Create A Stored Procedure on Sybase Adaptive Server

Create the following Stored Procedure on Sybase Adaptive Server (using the pubs2 database):

CREATE PROCEDURE dbo.sp_GetBooksByPrice
@minPrice money,
@maxPrice money,
@lowestPricedBook varchar(100) OUTPUT,
@highestPricedBook varchar(100) OUTPUT

AS
BEGIN
DECLARE @realminPrice money, @realmaxPrice money, @totalBooks int
SELECT * FROM titles WHERE price >=@minPrice AND price <=@maxPrice
SELECT @realminPrice = min(price) FROM titles WHERE price >=@minPrice
SELECT @realmaxPrice = max(price) FROM titles WHERE price <=@maxPrice
SELECT @lowestPricedBook =title FROM titles WHERE price = @realminPrice
SELECT @highestPricedBook =title FROM titles WHERE price = @realmaxPrice
SELECT @totalBooks = COUNT(title) FROM titles WHERE price >= @minPrice AND price <= @maxPrice
RETURN @totalBooks
END

The above Stored Procedure is a very typical one; it takes 2 input parameters and 2 output parameters. Running it, we will get one resultset, one return value and 2 output parameters values. Save the above SQL code as sp.sql. We will use it later on our Unix/Linux platform.

Open the PerlIDE application and input the following Perl code:

#!/usr/bin/perl

use strict;
use DBI;
my $server = “ibmxp”;
my $db = “pubs2″;
my $username = “sa”;
my $password = “”;

my $dbh = DBI->connect(”dbi:Sybase:$server”, $username,$password);
$dbh->do(”use $db”);
my $query = “declare @minPriceBook varchar(100), @maxPriceBook varchar(100)
exec sp_GetBooksByPrice @minPrice =2.00 , @maxPrice = 20.00, @lowestPricedBook = @minPriceBook OUTPUT, @highestPricedBook = @maxPriceBook OUTPUT”;
my $sth = $dbh->prepare($query);
$sth->execute();
do {
while(my $d = $sth->fetchrow_arrayref) {
if ($sth->{syb_result_type}==4040){
print join(”t”, @$d),”n”;
}
if ($sth->{syb_result_type}==4042){
print “The lowest price book is: “, $d->[0], “n”;
print “The highest price book is: “, $d->[1], “n”;
}
if ($sth->{syb_result_type}==4043){
print “There are total: “, $d->[0], ” books returnedn”;
}
}
} while($sth->{syb_more_results});
$sth=undef;
$dbh->disconnect;

Save the Perl code as sybase_sp.pl and from the command prompt window, issue the following command:

Perl sybase_sp.pl

We get the same result!

Please notice that the constant value used to identify $sth->{syb_result_type} comes from the Sybase CT-Library
API header file cspublic.h:

#define CS_ROW_RESULT (CS_INT)4040
#define CS_CURSOR_RESULT (CS_INT)4041
#define CS_PARAM_RESULT (CS_INT)4042
#define CS_STATUS_RESULT (CS_INT)4043
#define CS_MSG_RESULT (CS_INT)4044
#define CS_COMPUTE_RESULT (CS_INT)4045

We can use the same Perl code to execute the stored procedure on MS SQL Server 7.0 with service pack 2.

Open the SQL Server Query Analyzer, select the pubs database and run the above Stored Procedure code. You can check the Stored Procedure from SQL Server Enterprise Manager;

I use the Sybase dsedit utility to edit the Sybase interface file, and add my Microsoft SQL Server entry into the interface file. My machine name where MS SQL Server is installed is home2k; we can ping this server from the dsedit menu button, and make sure it is connected. See the following screenshots:

(You can also manually edit %SYBASE%inisql.ini. On Unix/Linux Sybase uses the file called interface in the $SYBASE root directory, same functionality as sql.ini)

Modify our Perl code as follows:

my $server = “home2k”;
my $db = “pubs”;

Other parts of the code remain unchanged. Run the code again, this time, we get the stored procedure running on MS SQL Server, and get the same result.

Save the above Perl code as mssql_sp.pl. We will use it on Unix/Linux platform later on.

See the source.

 

The PL/SQL Wrap Utility

Appendix C of the Oracle 9.2 PL/SQL User’s Guide and Reference covers the wrap utility. With many applications, it is common to see directories full of source code. Businesses can protect their intellectual property by taking proactive measures to protect and safeguard copyrighted material. If a company suspects copyright infringement is occurring, it is up to the company to seek legal remedies. This approach to protecting intellectual property (source code) is similar to closing the barn door after the cows have left. Perhaps the sheer number of files and lines of code serves as a deterrent to this type of theft.

If you or your company has developed algorithms that give your product a competitive edge in the marketplace, it makes sense that you would want to protect that code. All that needs to be exposed is the input. The internals of what happens to that input or how the output is produced can be likened to the black box approach in testing. With Oracle’s wrap utility, you can turn the inner workings of your code into an impenetrable black box, for the most part, to protect your property.

The “for the most part” caveat serves to alert you that wrap has some limitations. The reference guide, in part, states, “String literals, number literals and names of variables, tables and columns remain in plain text within the wrapped file. Wrapping a procedure helps to hide the algorithm and prevent reverse-engineering, but it is not a way to hide passwords or table names that you want to be secret.”

Oracle allows you to wrap the code inside the following statements:

 CREATE [OR REPLACE] FUNCTION function_name

 CREATE [OR REPLACE] PROCEDURE procedure_name

 CREATE [OR REPLACE] PACKAGE package_name

 CREATE [OR REPLACE] PACKAGE BODY package_name

 CREATE [OR REPLACE] TYPE type_name ... OBJECT

 CREATE [OR REPLACE] TYPE BODY type_name

A common practice is to leave specifications unwrapped and to wrap the implementation of procedures and functions within the package body.

Running the Wrap Utility

Wrapping a package is amazingly simple, although there is one pitfall to avoid. Among the 500 plus files in the ORACLE_HOME/bin directory you will see wrap or WRAP depending on your operating system (a lot of the more common files and directories on Windows are upper-cased for ease of readability and identification).

Using wrap is as simple as this:

c:ora9ibin wrap iname=input_file_name

You can specify an output file as a second argument by using this format:

c:ora9ibin wrap iname=input_file_name oname=output_file_name

Once wrapped, a package cannot be unwrapped. With that in mind, and just like what you would do with a real package, do not wrap the package until it is time to ship it. This implies keeping a source code repository of the original code. If a customer or user reports a bug against a wrapped package, there is no unwrapping it at the customer’s site. You are going to have to ship another wrapped package with the fix in it. You will be making the bug fix or enhancement with the repository file and wrapping the new file.

An Example of Using Wrap

In a previous article, I used the DBMS_RANDOM package. A slightly modified bit of code from that produces the following:

SQL> CREATE or REPLACE PROCEDURE wrap_it (seed_in NUMBER)

  2  IS

  3    v_rand INTEGER;

  4  BEGIN

  5    DBMS_RANDOM.INITIALIZE (seed_in);

  6    FOR i IN 1..5 LOOP

  7     v_rand := mod(abs(DBMS_RANDOM.RANDOM),45);

  8     dbms_output.put_line(i||': '||v_rand);

  9    END LOOP;

 10  END;

 11  /Procedure created.

SQL> exec wrap_it(123456);

1: 37

2: 36

3: 18

4: 8

5: 32

PL/SQL procedure successfully completed.

I can take the code for the wrap_it procedure and, well, wrap it. The code for the procedure is in a file named wrap_example.sql.

C:ora9i>wrap iname=c:ora9iadminwrap_example.sqlPL/SQL Wrapper: Release 10.1.0.2.0- Production on Thu Jul 15 22:11:18 2004

Copyright (c) 1993, 2004, Oracle.  All rights reserved.

Processing c:ora9iadminwrap_example.sql to wrap_example.plb

Note how Oracle changed the file extension to “plb.” Can we see the contents of the wrap_example.plb file? Sure, but will it be completely readable? Let’s find out.

Opening wrap_example.plb in my general-purpose text editor, we see the following lines of text:

CREATE or REPLACE PROCEDURE wrap_it wrapped

a000000

b2

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

abcd

7

e0 f7

uveH+zmPD1snPwtBZmL3T1hkxRcwgy7w154VfC9GAME+MzyOFMq0DNYH29gBazqoJJQ0Xemb

pdRvlWrC2UeKeKiS2uzT80HMAvKIMOYhjXZT4CrU98zgprrwl4jKnFKvFljUAnGx8GHexDSU

XRa3oykCJIUWEovu72mqAm0vttgZB9E/9E6y2HhxKdu1k8arcrHegHYAvF1pwn1e6sCFJg04

QGsN1g1JLYIklPGBDEEZInWt0w==/

That looks fairly undecipherable to me. One thing to note is the location of the output file. Using the example above, the new wrap_example.plb file was created in the c:\ora9i (my ORACLE_HOME) directory.

Now we know the procedure works and that the file or script can be wrapped. I will drop the procedure and re-create it using the plb file. If all goes well, I should be able to execute the procedure as before.

SQL> drop procedure wrap_it;Procedure dropped.

SQL> @c:ora9iwrap_example.plb

Procedure created.

SQL> exec wrap_it(123456);

1: 37

2: 36

3: 18

4: 8

5: 32

PL/SQL procedure successfully completed.

In Closing

The wrap utility is very easy to use, so if you have code you would like to protect, wrap it up. If the uncompiled or unwrapped version passes testing, so will the wrapped version because Oracle guarantees portability of the code.

What are some situations where you would want to wrap your code? Schema migration or alteration immediately comes to mind. Often times when there is a database migration (going to a newer version), you will find application developers or software manufacturers releasing a newer version of their product. The point release or major release version probably incorporates schema changes. Running wrapped update scripts helps protect your work. Keep in mind, though, that if a malicious user is dedicated enough, pretty much any schema can be reverse engineered, but why make it easy for him? Wrap it up and protect your work. And that’s a wrap.

See the source…

Look at the content of this file:

<?php$hostname="localhost";$username="root";

$password="pass";

$database="test";$connexion=mysql_connect($hostname,$username,$password)

or die ("Can't connect to the database!");

$db=mysql_select_db($database,$connexion)

or die ("Database not found!");

?>

mysql_connect() - we use this function for connecting to the database. This function has three parameters: the server name, the username and the password for connecting to the database. The $connexion variable can have two values: TRUE or FALSE depending on the MySql server connexion. In case it fails we will receive the message contained in the die() function.

mysql_select_db - this function will establish the database for connexion. This function has two parameters: the database name and the access identifier to the MySql server. The $db variable will contains the message in case the database is not found.

You can modify the content of the connexion file corresponding to your database configuration:

$hostname=the server address

$username=the username for connexion to the database

$password= the password for connexion to the database

$database=the database name

After all the operation made with the database we have to close the connexion using mysql_close() function.

mysql_close($connexion);

Combining WHERE Clauses

These can be used in two ways: AND clauses, OR clauses.

Operators: Specialized reserved words used for clauses unification or modification.

AND Operator

If you want to filter for more columns, use AND operator to add conditions to WHERE clause. The next code represent this:

SELECT prod_id,prod_price,prod_name FROMProducts WHERE  sale_id =´DLL01´ AND prod_price  <= 4;

I used this instruction to find out the name and price for all the products sold by the DLL01 seller as long as the price is maxim 4$. This WHERE clause is made by two conditions, and the reserved word AND is used for the unifications of the two specified conditions.

Remember: AND is used for finding the lines which correspond all the specified conditions.

OR Operator

This operator is opposite the AND operator. Using this operator the result will contains lines which correspond one condition. The most database systems won’t evaluate the second condition as long as the first is true.

SELECT prod_name, prod_price FROM Products WHERE  sale_id = ´DLL01´ OR  sale_id  =´BRS01´;

This instruction will find the name and the price for all the products of one of the 2 sellers.

Remember: OR is used for finding lines which correspond one of the specified condition.

The evaluation order

WHERE clauses may contain as many AND, OR clauses. Combining this two type of operators will allow for a sophisticated and complexed filtering. There is a problem in using both AND, OR operators. For example we need the products list which cost minimum 10$ and are sold by the DLL01 and BRS01 sellers. The below instruction contains a combination of AND and OR clauses for building a WHERE clause.

SELECT prod_name, prod_price FROM Products WHERE sale_id=´DLL01´ OR  sale_id =´BRS01´AND prod_price  > =10;

The result will be:

Pen  3.49, Pencil  3.49, Notebook  4.49, Book  11.9.

If you look the result will see that the first results don’t have corresponding values so there were a problem. Why this happened? The answer is the evaluation order. SQL as the most operating languages works with AND operators before OR operators. The earlier WHERE clause is interpreted this way: “show me products which cost 10$ or more sold by the DLL01 seller and all the products sold by BRS01 no matter the price“. So the conclusion is that the operators where unified in a wrong way. To solve this problem use brackets. So look at the below instruction:

SELECT prod_name,  prod _price FROM  Products WHERE  (sale_id  = ´DLL01´ OR  sale_id  =  ´BRS01´)

We know that brackets has a highest priority, first will be analyzed the condition OR. So now we can interpret the SQL command: “show me all the products of the seller DLL01 or BRS01 which cost 10$ or more“.

Remember: When you have WHERE clauses which uses AND, OR operators use brackets to group in an explicitly way the operators.

IN Operator

We use this operator to specify a condition domain. IN necessities a list of valid values, which should be separated by commas and contents in brackets. Lets have an example in this way:

SELECT prod_name, prod_price FROM  Products WHERE sale_id  IN  (´DLL01´  ,´BRS01´) ORDER BY prod_name;

We can observe that IN can be substitute by the OR operator. SQL will give us the same result as in the earlier example:

SELECT prod_name, prod_price FROM Products WHERE sale_id  =´DLL01´ OR  vanz_id = ´BRSO1´ORDER  BY  prod_name;

So what are the IN advantages? When we have long lists of values using IN it is easiest to read. Almost always the IN operators are executed faster then OR lists. The big advantage is that IN may contain another SELECT instruction and this way you can build WHERE clause in a dynamic way.

NOT Operator

The NOT operator has a single function - deny any condition that comes after. The syntax for this operator is different. The next example show us how to use this operator. If you want to display the products of all the sellers less DLL01, you can write:

SELECT prod_name FROM Products

WHERE NOT sale_id  =´DLL01´ORDER  BY prod_name;

The operator in this case deny the condition that comes after it. The NOT operator can be substitute with the “<>” operator. For simple clauses as we have here is not necessary using NOT operator. It can be used in complex clauses.

For a better understanding of the stored procedures importance I will give a definition and an example. A stored procedure is a subroutine available to applications accessing a relational database system. A stored procedure has a name, a list of parameters and SQL statements. Bellow is a simple procedure whose name is test and has an integer parameter. This procedure insert in person table the value “major” or “unknown” depending “a” variable. In this type of procedures we can use instructions like “IF ELSE END IF” like in the example below.

CREATE PROCEDURE test (IN a INTEGER)
BEGIN
  DECLARE age CHAR(10);  

  IF a = 18 THEN
    SET age = 'major';
  ELSE
    SET age = 'unknown';
  END IF;

  INSERT INTO person VALUES (age);

END

Why Stored Procedures

Stored procedures are something new for MySQL but this concept isn’t new for other DBMSs. The syntax is almost the same and there are people with experience, there are articles, tutorials and forums about stored procedure.

The performance is one of the greatest advantages of stored procedures. Stored procedures are faster because they are pre-compiled SQL code. MySQL server has some caching advantages. If you have a repetitive task with some requirements my advice is to call a procedure stored on the server. If a bunch of SQL statements are sent to the server, repeatedly, they have to be optimized each time. The SQL statements in the stored procedure that is in memory have to only be optimized once and an execution plan is created for the SQL statements in the stored procedure.

Another advantage of stored procedures is portability. If you write your stored procedure in SQL, you should know that it will run on every platform that MySQL runs on, without obliging you to install an additional runtime-environment package, or set permissions for program execution in the operating system. This is an SQL advantage rather than an external language like Java, C++, PHP.

Since the procedures are stored on the server there is an easy maintenance and we can make changes in one place rather than to a lot of SQL statements distributed all over the application.

We can create procedures who can permit the users to access some databases, rather than giving them full access. So this can be like security measurements.

Part II will come!

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• Consolidate data from many different databases
• Easy interface for Business Intelligence Analysis

Excel-DB for DBA’s:

• Stop those “Why can’t I get my own data?” complaints
• Quickly deploy database-enabled spreadsheets to your end-users
• Safely deploy data without security risk
• Get Business intelligence extraction with native SQL
• Perform advanced analytics without expensive new tools

Excel-DB is great for the SQL Server user and you can get your SQL Server data into your spreadsheet with a built-in toolbar. There is no need to buy expensive Business intelligence or data warehouse solutions for SQL Server, since all you need to do is download your SQL Server tables right into your spreadsheet.

Excel-DB is the perfect interface for SQL Server data. You can directly extract and analyze current SQL Server data, right in your excel spreadsheet and without cumbersome Microsoft ODBC.

Using Excel-DB is the best way to get Oracle data into your Excel spreadsheets and it has a native API, directly into your Oracle database. Get Oracle tables into Excel!

Excel-DB gives you a direct and easy way to extract and analyze your MySQL data, right from your Excel Spreadsheet.

For more details about the product or about ordering Excel-DB visit http://www.excel-db.net/

Did you ever tried to work with some databases that contain big tables? And by BIG I mean one table at least that has more than 1 million records. No matter you are using MySql, SqlServer, Oracle or other DBMS, the problem is same: finding informations in that table ( records as we all know them) is very very slow. Can take minutes if the database is big and that’s really a pain. (more…)