IT-angel's Blog

Oracle PL/SQL splitting function

itangel — Mon, 02 Nov 2009 08:19:01 +0000

I needed to spilt (tokenize) a string in Oracle SQL and I wanted do it simply and I found a really useful function:

function get_split(the_list varchar2, the_index number, delim varchar2 := '|' ) return varchar2 is start_pos number; end_pos number; begin if the_index = 1 then start_pos := 1; else start_pos := instr(the_list, delim, 1, the_index - 1); if start_pos = 0 then return null; else start_pos := start_pos + length(delim); end if; end if; end_pos := instr(the_list, delim, start_pos, 1); if end_pos = 0 then return substr(the_list, start_pos); else return substr(the_list, start_pos, end_pos - start_pos); end if; end get_split;

So now I could do a select :
select get_split('0|1|0',2) from dual; –> ’1′

ORA-02270: no matching unique or primary key for this column-list

itangel — Thu, 22 Oct 2009 08:56:50 +0000

I generated this error today and the error source of this has been described as follows:

Cause: A REFERENCES clause in a CREATE/ALTER TABLE statement gives a column-list for which there is no matching unique or primary key constraint in the referenced table.

Action: Find the correct column names using the ALL_CONS_COLUMNS catalog view.

I wanted to add a foreign key constraint to a table and actually the column being referenced had an unique index.

I created an unique index in primary table:

create unique index UNIQUE_INX_TEST1_ID

on PRIMARY_TEST1 (TEST1_ID);

but I forgot that I must add a unique constraint on PRIMARY_TEST1 as well, referencing the unique index we’ve just created:

alter table PRIMARY_TEST1 add constraint PRIMARY_TEST1_UQ

unique (TEST1_ID)

using index UNIQUE_INX_TEST1_ID;

and now I can add a foreign key conraint to another table referencing to this unique index column.

Marking all mail as read in Gmail

itangel — Fri, 16 Oct 2009 12:57:42 +0000

Need to mark a lot of emails as read? I had over 800 unread emails in my Gmail inbox and I wanted to mark messages as read without marking those individually.

What you need to do:

1. You need to find all unread messages, you can do that by typing “is:unread” in the search box

2. Press “All” in the select area

3. Gmail added an option in search results to select conversations that match a search. After done all previous steps you need do press a new appearing link “Select all conversations that match this search“

4. Now all unread messages are marked and you can choose “Mark All as Read” from the drop down.

This is a quick and simple way to mark your unread messages as read and you can repeat it whenever your messages count goes out of bounds.

Determine start date and end date of the year

itangel — Wed, 14 Oct 2009 10:48:06 +0000

I needed to find out what is the first day and the last day of this year in Oracle PL/SQL. We don’t like to update the date parameters of the queries, so we needed queries that can be used by many users without changing them every year.
What I found out:

This year’s first day is :

SELECT TRUNC(SYSDATE,’SYYYY’) from dual;

SYYYY means that all four digits of the year are with a negative sign (-) for B.C.
and this year’s last day:

SELECT LAST_DAY(ADD_MONTHS(TRUNC(SYSDATE,’SYYYY’), 11)) FROM DUAL;

But if you would like to know the first and the last day of last year:

the first day of last year

SELECT TRUNC(ADD_MONTHS(SYSDATE, -12),’SYYYY’) from dual;

and the last day of last year:

SELECT LAST_DAY(ADD_MONTHS(TRUNC(ADD_MONTHS(SYSDATE, -12),’SYYYY’), 11)) FROM DUAL;

Well, if you would like to know the first and the last day of next year, you should change “-12″ to just “12″.