Get extra records between two tables - Oracle

Here are examples of each when you wish to see matching data and data differences between two tables.

Example:
You have primary Person Table that has 100 records, unique identifier person_id,
then you have a another Table Person_Depts with only 63 records that has Person_id.

Table : Persons
person_id number,
person_name, etc...

Table : Person_Dept
person_id number,
dept_id number,
status char(1), etc...

When you wish to find the 63 matching records it's easy:

select distinct
from persons p,
person_dept pd
where p.person_id = pd.person_id

When you wish to return the 37 rows of the persons in person_dept and do not have a match in persons, you extract them using one of the followig two queries:

select distinct pd.person_id from person_dept pd
minus
select p.person_id from persons p

Or you could use the following lines on small sets of data, using this on long non-indexed tables

select tp.person_ID
from
person_dept tp
where (tp.person_ID ) NOT IN ( select p.person_id from persons p)

update one table with data from another table

This blog post illustrates how to update more than one column in a table with values from columns in another table and explains how to do it in two RDBMS that I use.

Table Structures and values:
TableA has four columns: a, b, c, d (a is the primary key column)
TableB has five columns: a1, b1, c1, d1, e1 (a1 and b1 together constitute the primary key for this table)
The foreign key relationship between the two tables is based on A.a = B.a1
The data in these 2 tables is as follows:
I. TableA
a b c d
1 x y z
2 a b c
3 t x z

II. TableB
a1 b1 c1 d1 e1
1 x1 y1 z1 40
2 a1 b1 c1 50

The requirement is to write a SQL to update columns b, c and d in TableA from the columns b1, c1 and d1 from TableB where-ever the join condition satisfies and e1 > 40 in TABLEB.

Oracle:
UPDATE TABLEASET (b, c, d) = (SELECT b1, c1, d1 from TABLEB WHERE TABLEB.a1 = TABLEA.a and TABLEB.e1 > 40)WHERE EXISTS (SELECT 1 from TABLEB WHERE TABLEB.a1 = TABLEA.a and TABLEB.e1 > 40)
/

Results after the update:
a b c d
————————————
1 x y z
2 a1 b1 c1
3 t x z


SQL Server:
UPDATE TABLEA
SET b = TABLEB.b1,
c = TABLEB.c1,
d = TABLEB.d1
FROM TABLEA, TABLEB
WHERE TABLEA.a = TABLEB.a1
AND TABLEB.e1 > 40
GO

Note: This is an extension in SQL Server i.e. the FROM clause – it does make it simple to understand and is a nice feature.
Results after the update:
a b c d
————————————
1 x y z
2 a1 b1 c1
3 t x z



Happy writing SQL

Alter table column

This is something so simple, yet can cause you to pull your hair out. All you want to do is alter the length of a column in an Oracle table:

An example table:
Members
MbrID number(5)
FirstName varchar2(30)
Surname varchar2(30)

Now you wish to increase the length of the surname to 50 characters, as someone has a longer than usual surname.
Here is the syntax to do this:

alter table members
modify surname varchar2(50)

This has now been updated to :
Members
MbrID char(5)
FirstName varchar2(30)
Surname varchar2(50)


When you wish to add a column:
alter table members
add DateOfBirth date

When you wish to remove a column:
alter table members
drop column DateOfBirth

When you wish to rename a column
alter table customers
rename column surname to lastname

Find and replace text in MySQL and Oracle

Today someone told me that they have a blog with over 300 posts and just changed their URL, the problem is that the new blog still had reference to their previous blog's url. And all the images, and reference were to the previous URL which had a 401 re-direct to the new blog. The images, etc were already deleted from the previous blog and imported into the new URL.

He was actually going to update every single entry. I recommended that it the blog has all posts in it's SQL database and had to find all the fields which contained the text (old url address), with the new text (new url ).

Now I will show you and easy way to update this.

Go to your database SQL screen and type in as follows

UPDATE [your_table_name] SET [your_table_field] = REPLACE([your_table_field], '[string_to_find]' , '[string_to_be_replaced]');

example
UPDATE my_posts SET post_content = REPLACE(post_content, 'www.oldurl.com' , 'www.newurl.com');

So armed with only one query per column table combination, you can easily update your blog or database with the new text.

Setting preferred domain

When search engines find your website, they may come across, http://yourdomain.com or http://www.yourdomain.com, which is read as two domains, causing duplicate listings. To fix this you have to decide which web domain will be the preferred domain.

To set your domain in google, go to the www.google.com/webmasters/tools/ website and set your preferred domain.

After you set the preferred domain, you should force everyone to use this domain with a 301 redirect. You do this by editing your root .htaccess file, if hosted on a Linux server. If you do not have a .htaccess file you will need to create one first as follows:

1) Create a text file and name it .htaccess
2) Modify it with the preferred domain code (as details below)
3) Upload it to the root of your server (public www)

If you want people to redirect from non-WWW to WWW:
(for example, if someone types in http://yourdomain.com, it will forward to http://www.yourdomain.com)

RewriteEngine On
RewriteCond %{HTTP_HOST} !^(.*)\.yourdomain\.com$ [NC]
RewriteRule ^(.*)$ http://www.yourdomain.com/$1 [R=301,L]

If you want people to redirect from WWW to non-WWW:
(for example, if someone types in http://www.yourdomain.com, it will forward to http://yourdomain.com)

RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.yourdomain\.com$ [NC]
RewriteRule ^.*$ http://yourdomain.com%{REQUEST_URI} [R=301,L]

Don't forget to replace “yourdomain” with the URL of your domain, otherwise the code above won't work!

Therefore by setting a preferred domain you are ensuring that Google and all the major search engines will only index your url web links from one domain. This will help your PageRank in search engine rankings.

So don't put it off, set your preferred domain, if you have not done so already! You will see your PageRank rise!

Combine text using Concatenation in Oracle

When wanting to combine text you can use the concatenation operator

Examples:
To place comma after every row returned use as follows:
SELECT table_name ',' FROM user_tables;

You may have a date that you wish to place in a CSV file, you can concentate as follows:
SELECT 'the date today is: ' to_char(sysdate, 'MM-DD-YYYY') ',' FROM sys.dual;

Reverse function in Oracle

The following shows how to use the reverse function to reverse a string or number in Oracle.
SQL> select reverse('string') from dual;
REVERS
------
gnirts

However you may not have the function installed and can use the following procedure:
SQL>
SQL> create or replace procedure reverse(x in varchar2) as
2 a char(1);
3 i number;
4 begin
5 for i in 1..length(x) loop
6 select substr(x,length(x)-i+1,1) into c from dual;
7 dbms_output.put(a);
8 end loop;
9 dbms_output.put_line(' ');
10 end;
11 /


Procedure created.

SQL> set serverout on
SQL> exec reverse('Oracle')
elcarO

SQL> exec reverse('string')
gnirts
PL/SQL procedure successfully completed.

Get last 2 financial years quarters

The 'solution' below is to retrieve the start and end dates of annual quarters of the last 2 years, using the @end_date as your input parameter.

You can replace the '--- YOUR QUERY USING the @qtr_start and @qtr_end parameters' with your query, with the @qtr_start and @qtr_end as your search criteria.


DECLARE
@qtr_start DATETIME,
@qtr_end DATETIME,
@end_date DATETIME

-- your date parameter
SET @end_date = '2009-06-30'

-- initialise dates
SET @qtr_start = DATEADD(YYYY, -2, DATEADD(D,1, @end_date))
SET @qtr_end = DATEADD(DD, -1,DATEADD(M,3,@qtr_start))


WHILE @qtr_end <= @end_date
BEGIN
SELECT 'Quarter: '+convert(VARCHAR, @qtr_start, 3)+'-'+convert(VARCHAR, @qtr_end, 3),
@qtr_start,
@qtr_end

--- YOUR QUERY USING the @qtr_start and @qtr_end parameters

-- get rest of the quarters until end date
SET @qtr_start = DATEADD(DD, 1,@qtr_end)
SET @qtr_end = DATEADD(DD, -1,DATEADD(M,3,@qtr_start))
END

Display html php code in blogger

When posting the PHP menu post, I found the post to distort the html and php sections and found the following to blog which assist to fix the display html in Blogger or even Wordpress issue:

display html, javascript and php code in blogger

PHP Include menu and footer

Header and Footer Inclusion

This is a beginners tutorial on how to create and include header/footer files at the top and bottom of all pages in your site. This comes in very handy, for example, when you want to update something that is the same on each page such as a menu or copyright notice. You would only need to update a single file to have the changes appear on all pages of your site.

Let's pretend you wish to create have 20 web pages for your site with the same design and you want to change a link in your menu. You would have to edit all 20 pages, right? Nope, there's a much quicker way allowing you to edit just one file for the mene or footer and really it's not as hard as it sounds.

What you have to do is create a header file and a footer file. The header file contains all the HTML code for the top portion of your site. The footer contains the HTML for the bottom. Content goes between the header and footer. Let's get started...

This is an entire HTML document to give you an idea of what the header and footer are and where the content fits in. The header is in blue, content is in red, and footer is in green.

create a file named :
---------------------------------------------------
index.html
---------------------------------------------------
<html>
<head>
<title>Title of your website</title>
</head>
<body text=black link=blue alink=red vlink=purple>

<!--- menu at the top --->
<p align=center>
<a href='index.html'>Home</a> | <a href='about.html'>About My Site</a> | <a href='links.html'>Links</a>
</p>

This is the content of a page on my site.

<p align=center>Copyright 2009. All Rights Reserved</p>

</body>
</html>


---------------------------------------------------

After determining which portions are the header and footer, you need to cut and paste them into new files, lets name them header.html and footer.html.
The index.html file you are using as an example should only contain the content after this. Here's an example of how things are divided up.

---------------------------------------------------
header.html <html>
---------------------------------------------------
<head>
<title>Title of Site</title>
</head>
<body text=black link=blue alink=red vlink=purple>

<!--- menu at the top --->
<p align=center>
<a href='index.html'>Home</a> | <a href='about.html'>About My Site</a> | <a href='links.html'>Links</a>
</p>
---------------------------------------------------


---------------------------------------------------
footer.html
---------------------------------------------------
<p align=center>Copyright 2002. All Rights Reserved</p>

</body>
</html>


---------------------------------------------------
index.html
---------------------------------------------------
This is the content of a page on my site.
---------------------------------------------------


You now have header and footer HTML code in their own files. This means we can include these two files at the top and bottom (with content between) of any number of pages on our site. This is very convenient! For example, if you wanted to change a link in your menu, you would just edit it in header.html instead of every page of your site!


Now you only want to call the index page and have the header.html and footer.html included. The way to do this is to rename the page to index.php or anything.php as and add the follows:

---------------------------------------------------
index.php or anything.php for other pages on your site
---------------------------------------------------
<? include("header.html"); ?>

This is the content of a page on my site.

<? include("footer.html"); ?>
---------------------------------------------------