Shantanu's Blog

Corporate Consultant

October 20, 2006

 

MySQL Case Study - 122

How do I find the first 'N' rows of each group?

For example: Table (type, serial#), with data
('X', 1000)
('X', 1001)
('X', 1003)
('X', 1010)
('Y', 1002)
('Y', 1005)
('Y', 1011)
('Z', 1015)

How would I retrieve at most 2 rows for each type?

('X', 1000)
('X', 1001)
('Y', 1002)
('Y', 1011)
('Z', 1015)

http://forums.mysql.com/read.php?10,122329,122329#msg-122329

 

MySQL Case Study - 121

A table has a group of items that have unique entries for images. But the image is really the same for each group so I need to rename those. So a table entry might look like
table products {
name;
image;
}
and the data would be

name = a1 image - a-1.jpg
name = a2 image - a-2.jpg

I want it to end up being

name = a1 image - a.jpg
name = a2 image - a.jpg

I was thinking to use the update command but can't see what to put in the set option:
update products set image=??? where image like '%-%.jpg'

If it were just one group, I could just put the image name in it. But there are about 9,000 products so I need something automatic. Would someone please explain how to do this?

http://forums.mysql.com/read.php?10,122378,122378#msg-122378

October 19, 2006

 

Excel Tips

1) How do I count the number of "red" items which cost less than $1000?
=SUMPRODUCT((C2:C6<1000)*(B2:B6="red"))

2) Summing Values in a Range Containing Redundant Spaces

If a numbers in column A contain redundant spaces, the SUM function - 0 is returned.

Use the SUM, VALUE, and SUBSTITUTE functions as shown in the following Array formula:
{=SUM(VALUE(SUBSTITUTE(A2:A4," ","")))}

3) How do I convert the sequence of First Name and Last Name?

I want to convert the full names in column A, formatted as "LastName, FirstName" into names formatted "FirstName LastName".

Use the RIGHT, LEFT, LEN and FIND text category functions, as follows:
=RIGHT(A2,LEN(A2)-FIND("","",A2)-1)&"" ""&LEFT(A2,FIND("","",A2)-1)

4) Getting a Count of Unique Names

if there are no blank cells in column B,
you can use an array formula (entered by Ctrl+Shift+Enter):
=SUM(1/COUNTIF(B2:B50,B2:B50))

 

Mysql tip : Convert Time Zone

CONVERT_TZ(dt, from_tz, to_tz)

CONVERT_TZ() converts a datetime value dt from the time zone given by from_tz to the time zone given by to_tz and returns the resulting value. This function returns NULL if the arguments are invalid.

If the value falls out of the supported range of the TIMESTAMP type when converted from from_tz to UTC, no conversion occurs.

mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','GMT','MET');
-> '2004-01-01 13:00:00'

mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','+00:00','+10:00');
-> '2004-01-01 22:00:00'

Note: To use named time zones such as 'MET' or 'Europe/Moscow', the time zone tables must be properly set up.

October 14, 2006

 

Marathi Spell check within your word processor

Here is a quick check-list if you want to be able to use Indian Language in your word processor. (And spell check your word as well!)

A) Open Office
You will first have to download and install English version of Open Office from here...

http://download.openoffice.org

B) Baraha

Download and install BarahaIME (Baraha Input Method Editor) from here...

http://www.baraha.com/download/BarahaIMESetup.exe

C) Install Marathi Dictionary

1) Start - Programs - OpenOffice.org 2.0 - openoffice.org writer
2) File - Wizards - install new directories...
3) Click on "English" link
4) Click on "Start DicOOo" button.
5) Current user setup
6) Click on "Retrieve the list" option.
7) Choose "Marathi (India)" from the list and click on Next.
8) "Hyphenation" and "Thesaurus" dictionaries are still not uploaded. So don't select anything and simply click on "Next>>" twice.
9) Click on next to start the download
10) Click on finish.
11) Completely exit openoffice (all windows!)
12) Close the Quickstarter by right clicking on it's icon near the clock.
13) Start openoffice.org writer
14) Tools - Options - - Language Settings - Languages
15) Select Marathi under "CTL" option.

That's it.

OR
Download and install the dictionary from here...
http://extensions.services.openoffice.org/en/project/dict-mr

Now if you are using Baraha software just hit F11 and start typing in Marathi. The misspelled words will be automatically underlined in red.
You can also install the hindi, Gujarati and other language dictionaries.

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