Hamid Reza Fahimi

sql IN logical operation for java

2009-04-20T17:24:00.004+04:30

Hi,
have you ever needed sql IN for java language ?
OK, in this post I'm going to use new java 5 feature (varargs method) to simulate sql IN:

public static boolean in(int i, int... ints) {
 Arrays.sort(ints);
 return Arrays.binarySearch(ints, i) >= 0;
}

as you see, our function gets 2 parameters, first one is your desired value and second one is your search list.
now, when you call the method:

public static void main(String[] args) {
   System.out.println(in(1, 2, 3, 4, 5, 1));
}

it returns:

true

i hope you find this tip useful;

backup from mysql database's routines

2009-04-11T16:58:00.007+04:30

Sometimes we need get backup just from mysql database's routines.
command below shows us how we can do that:

mysqldump dbname -uusername -p -Rtd > /path/to/your/dump/file

-u username
-p prompt password
-R stored procedures and functions
-t prevent writing table creation
-d "       "       row information

how to detecet is there persian alphabet(s) in a string via php?

2008-05-27T12:33:00.008+04:30

Because our system should detect direction of a string, we need a function that tell us the string has Persian alphabet or no,
so i write a little function to check it for us:


function hasPersianAlphabet($str) {
$persianAlphabet = array('ا', 'ب', 'پ',
'ت', 'ث', 'ج', 'چ', 'ح', 'خ', 'د',
'ذ', 'ر', 'ز', 'ژ', 'ط', 'ظ', 'س',
'ش', 'ض', 'ص', 'ع', 'غ', 'ف', 'ق',
'ك', 'ک', 'گ', 'ل', 'م', 'ن', 'و',
'ه', 'ي', 'ی', 'ه', 'آ', 'ء', 'ئ', 'ة');
str_ireplace($persianAlphabet, '', $str, $count);
return $count > 0;
}

how to deploy war file into web root ?

2008-05-07T15:28:00.003+04:30

Some times we need deploy our peoject into root directory of your domain (not sub directory), to solve the problem:

make war file (for example myproject.war)
rename the war file to ROOT.war (attention the filename must be uppercase)
deploy war file

now, you can see / in tomcat web application manager page that deployed in site root.

how to get all oracle components version ?

2008-03-03T17:54:00.007+03:30

You can use 2 queries to get oracle components version:

1. select * from product_component_version

in this case you get result like below


PRODUCT                  VERSION   STATUS
---------------------------------------------
NLSRTL                   9.2.0.1.0 Production
Oracle9i Enterprise E... 9.2.0.1.0 Production
PL/SQL                   9.2.0.1.0 Production
TNS for Solaris:         9.2.0.1.0 Production

all fields have crystal clear contents, so i won't describe them

or

2. select * from v$version

that returns same result as above but all fields is concated


BANNER
---------------------------------------------
Oracle9i Enterprise Edition Release 9.2...
PL/SQL Release 9.2.0.1.0 - Production
CORE 9.2.0.1.0 Production
TNS for Solaris: Version 9.2.0.1.0 - Produ...
NLSRTL Version 9.2.0.1.0 - Production

90, 7, 3 rule

2008-01-30T09:25:00.000+03:30

Few days ago, my boss told me a rule in software projects (or maybe other projects).
The rule called 90, 7, 3 rule ! which means:

90 percent of project is thinking
7 percent is implementing
and
3 percent is debugging

isn't it fantastic ?

Maybe some developers do vice versa!

I hope we were not who developers that did 90% implementing, 7% debugging and 3% thinking!

temporary/memory tables in mysql

2008-01-21T17:36:00.000+03:30

As you know memory tables (temporary tables) are a kind of tables which store data in memory and respond to your query very fast.
I've experienced temporary tables in Oracle and SQL Server by myself but I had no practical experience about that in mysql till yesterday!
Yesterday, I had a query that was very slow and took 4-5 hours for running! So I started to search about temporary tables in mysql and found how to use them.
After I used memory table in my queries, it took only 9 minutes !!! It was unbelievable.
So I decied to post a new mini article here and share result of my research with you.

There is a very simple command for creating a memory table :

create table tbl1(fld varchar(64)) engine=memory;

This commands will create a table in memory for us but it's empty. Now, how we can fill it ? We can use insert command for filling this table or fill it on creation time:

create table my_table engine=memory
select ip,country from ip_location;

As you see it's like a piece of cake ;)
Now we have a table in memory which help to decrease our query run time. if you get

Error Code : 1114
The table 'my_table' is full

error message during creation memory table, you have some solutions to solve the problem:

1. increase max_heap_table_size system variables.

 set @@max_heap_table_size=1048576
/* your favorite size in byte, it's 1 MB */

It's a system variables that force maximum size on memory tables

2. limit rows by max_rows table option. It's a table option in the create table statement to keep the table from becoming too large

3. decrease length of fields type, for example if you have a field as varchar(100) change it to varchar(32)

After creation, the table will be accessible for all sessions till server doesn't restart or shut down, after that you have your memory table without any rows.

You can read a complete document about memory tables here.

The solution solved my problems, I wish you enjoyed it :)

Set JFreeChart data from database

2008-01-15T16:40:00.000+03:30

A couple of days ago I needed to generate some charts using Java so I searched for a library which could do it. Soon I found JFreeChart library and downloaded it from here. But I was surprised when I saw the user guide wasn't free! Therefore I decided to write this post and describe how to obtain JFreeChart data from database (I'll use mysql database).

At first I copied jcommon-1.0.12.jar, jfreechart-1.0.9.jar and mysql-connector-java-5.0.7-bin.jar files to /WEB-INF/lib directory then I created a table in the database and filled it with below data:


type             count
----------------------
invoice_detail    3273
----------------------
object_status     2819
----------------------
service_sales_... 1540
----------------------
call_function     1183
----------------------
contact           904
----------------------
invoice           775
----------------------
payment           596

Now I create DatabaseChart servlet for connecting to database and generating my chart


import org.jfree.data.jdbc.JDBCPieDataset;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import java.io.OutputStream;
import java.sql.SQLException;
import java.sql.DriverManager;
import java.sql.Connection;

public class DatabaseChart extends HttpServlet {

public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {}

public void doGet(HttpServletRequest request,
HttpServletResponse response)
 throws ServletException, IOException {
Connection connection = null;
try {
 Class.forName("com.mysql.jdbc.Driver").
newInstance();
 try {
     connection = DriverManager.
getConnection("jdbc:mysql://localhost/
my_db?user=my_un&password=my_pass&
useUnicode=true&
characterEncoding=utf-8");
 } catch (SQLException e) {
     e.printStackTrace();
 }
} catch (InstantiationException e) {
 e.printStackTrace();
} catch (IllegalAccessException e) {
 e.printStackTrace();
} catch (ClassNotFoundException e) {
 e.printStackTrace();
}

JDBCPieDataset dataset =
new JDBCPieDataset(connection);
try {
 dataset.executeQuery("Select `type`, `count`
From my_table order by count desc");
 JFreeChart chart = ChartFactory.
createPieChart("Pie Chart", dataset,
true, true, false);
 if (chart != null) {
     response.setContentType("image/png");
     OutputStream out = response.
     getOutputStream();
     ChartUtilities.writeChartAsPNG(out,
       chart, 450, 400);
 }
} catch (SQLException e) {
 e.printStackTrace();
}
try {if(connection != null){connection.close();
}}
catch (SQLException e) {e.printStackTrace();}
}

}

at the end I add the servlet information to web.xml file

 <servlet>
<servlet-name>generate_chart</servlet-name>
<servlet-class>DatabaseChart</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>generate_chart</servlet-name>
<url-pattern>/generate_chart</url-pattern>
</servlet-mapping>

now if you run the project you will get a chart like this

How to search and sort primitive arrays in Java ?

2008-01-07T16:19:00.000+03:30

Always I was keen on solution for sorting and searching primitive arrays. Today I found java.util.Arrays class that includes some useful static methods for sorting, searching, filling and ... For sorting you can use Arrays.sort(aPrimitiveArray) static method, look here :

String[] test = {"d", "z", "a"};
Arrays.sort(test);
System.out.println(Arrays.toString(test));

The result will be:

[a, d, z]

As you see we've used Arrays.toString(test) for printing sorted array.

And for searching you can use Arrays.binarySearch(aPrimitiveArray, key) static method:

Arrays.sort(test);
System.out.println(Arrays.toString(test));
System.out.println(Arrays.binarySearch(test, "a"));

The result will be:

[a, d, z]
1

1 is index of found key otherwise it will be a less than zero number.

Attention: that before using Arrays.binarySearch(aPrimitiveArray, key) method you have to sort array by Arrays.sort(aPrimitiveArray) method.

boring English teacher!

2008-01-03T14:51:00.000+03:30

Two days ago English teacher was absent. she went to holidays because she is Christian.
Instead another teacher came for teaching us. I think she was illiterate, she couldn't speak English fluent and when we asked her about new word she said "I'm not dictionary, check your dictionary please"!

The class was boring and all of us yawned frequently :D
In break time we went to institute office and talked with our supervisor for leaving class but he said "It's very impolite, please stay till end of class"! and we were forced to tolerate that stupid teacher!

deploy war file without lib in Tomcat

2007-12-26T16:12:00.000+03:30

At this post I'd talk about how to decrease size of big war files and make deployment faster.
I have a 15 MB war file and the size of lib (jar files) directory is 14.8 MB! So I need a solution that enables me to upload my project lib directory just for once and after that deploy my war file without lib directory.

At first I renamed my lib directory to myprojlib and then copied (for example using ftp) it to ${tomcat home}/common/lib folder on the server.
After that I modify catalina.properties file in ${tomcat home}/conf and add my myprojlib path to common.loader according below:

common.loader=${catalina.home}/common/classes,
${catalina.home}/common/i18n/*.jar,
${catalina.home}/common/endorsed/*.jar,
${catalina.home}/common/lib/*.jar,
${catalina.home}/common/lib/myprojlib/*.jar

Now save the file and restart my Tomcat.

After that I remove lib folder from my project and compile it without lib directory. Be careful don't package jar files in your project. My war file is
180KB now and I deploy it easily and I shouldn’t deploy 15 MB war file every time.

advantages and disadvantages of software developing as a job

2007-12-25T15:08:00.000+03:30

2 days ago my English teacher asked me that wrote a note about advantages and disadvantages of my job.

Today, I'm going to talk about advantages and disadvantages of Software Developing as a job. However it's my current job and I'm indisputable satisfied with that, but I promise I'll write about that candidly.

At first let's talk about advantages of Software Developing.
As you know, nowadays IT (Information Technology) is using in any kind of industries and careers so you have a variety job opportunities that help you find your ideal job. In addition salaries are good, if you can achieve to middle level knowledge about your field you will have a reasonable salaries. Also according that job you will be up-to-date and know today’s knowledge.

And about disadvantages...

One of them is sore eyes, yes; it's a real about who work with computers more than 2-3 hours a day.
And another bad thing is backache, because you sit back of compute for long time without any movement.
Also the worst disadvantages is (in my opinion) you don't have any deal with people and you should engage in stupid computer ;)

As you see, I mentioned just 3 cons and pros about my job but there are a lot that I didn't write about them.
I think every body can increase advantages of his/her job and decrease disadvantage of that.
For example, I can improve my knowledge for making more money and getting promotion, have a regular sport program for avoiding illness and company in social activities for making up deal with computer.

first wintery mountain climbing

2007-12-22T17:42:00.000+03:30

1. My wife and I went to first wintery mountain climbing on Friday. The weather was cold (around -6 C) but it's sunny. At first we had some problems with our ice creepers but i found their temper ;)

Everything was ok but when we was returning my knee got pain. One or two month ago I went to doctor and he said "it's not important , but you should strengthen your knee" !

Anyhow that was fantastic for us. You can see some pictures about that below.

2. Today my intellij IDEA made me crazy, when I compiled and ran my j2ee App, appeared situation as coma after one or two click on links! I couldn't understand what's wrong. God, help me :(

3. I found a page that lists all irregular verbs in English language, enjoy it.

Hello World !

2007-12-19T16:19:00.000+03:30

It's my first post in blogger just for improving my English language skill !
I'm decided on write about my interesting things like programming(J2EE, PHP 5, MySQL, Oracle), climbing, music, life and ...
don't be lazy! follow my blog if you like finding out more ;)