a glimpse from the past

at last... after more than 3 months of searching.. i found my lovely song..
check the great koko-wawa

Comments

Post a Comment

Popular posts from this blog

Prime Numbers Generator

Image
did u know that 34136029 is a prime number?!! well.. that's what i recently realized :) I thought of writing a piece of code for that purpose.. wondering how far i can get. The idea of the code is simple We know that 2 and 3 are prime numbers the code checks every following odd numbers to be prime or not. To verify a prime number, the number divisibility by the prime numbers generated so far is checked. (29 is a prime number.. because it id not divisible by 2, 3, 5, 7, 11, 13, 17, 19 nor 23) We only need to verify divisibility against the numbers smaller than or equal to the root of the number in hand. (We needn't check the divisibility of 33 with 11, as we already must have found out it is divisible by 3).. I did not want to go with the mathematical root evaluation as i am not sure about its load. I used bits handling instead. the root of a number uses at most half of the number of bits that the original number uses. i only made a naive java implementation so far. downloa
Read more

has_and_belongs_to_many & Duplicate entry Error

In one of my Rails projects at eSpace , i had a Many to Many association between two models. this allowed me to look more deeply into the has_and_belongs_to_many association. When you say: class Question < ActiveRecord::Base    has_and_belongs_to_many :surveys end class Survey < ActiveRecord::Base    has_and_belongs_to_many :questions end Rails will assume there is a table questions_surveys that include foreign keys to the two entities. So this table should be created by the following migration create_table :questions_surveys,:id => false do |t|     t.integer :question_id, :null => false     t.integer :survey_id, :null => false end :id=>false will prevent the creation of the default primary key for that table.This is very important for has_and_belongs_to_many associations. as the API documentation say; other attributes in thatrelation will be loaded with the objects and will be read only, including the :id. So failing to disable the id generationfor that table w
Read more

Exporting data from remote mysql instance in csv, using mysql client and sed

Mysql allows exporting query results to csv using the INTO OUTFILE , like the following example: SELECT a,b,a+b INTO OUTFILE '/tmp/result.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n' FROM test_table; This, however, will cause the data to be exported to the file system of the database server.  Sometimes you do not have access to that server and you are only connected remotely from a different machine using mysql command line. One way to export the data is to pass a query and redirect the output to a file as follows $ mysql -u USERNAME -p PASSWORD -h DB_SERVER mydb -e "SELECT a,b,a+b INTO OUTFILE FROM test_table;" > output.txt This will do the trick, except that the resulting file is TAB separated instead of CSV. You can simply download the file and open it using any text editor and replace all tabs with commas. but that's not practical for large data sets.  Instead, we
Read more