Dev Corner

How to store and order date and time in SQLite

bateto — Fri, 12 Aug 2011 20:02:19 +0000

In SQLite there is no class used for storing date and time. But there are still some handful functions, which are for working with time information.

1. How to get the current date and time ?

SELECT datetime(‘now’)

In this query the string ‘now’, is converted into the current date and time in the format YYYY-MM-DD HH:MM:SS. But SQLite does not support date arithmetic for this format.

2. Receive the current time as an integer

SELECT strftime('%s',’now’)

This query uses the function strftime, which returns the current time as Unix Time – the passed seconds since 1970-01-01. Universal Coordinated Time (UTC) is used. This is much more useful format, because it is an integer data, which is supported by SQLite data class. This means that arithmetical calculations could be made using the result from this query. Also, this data in this format could be easily ordered and stored. Even, if we want to store the moment, that a row is inserted in a table, we could use a column for the date and time, using a default value the result of this function.

3. Get the result back

SELECT datetime(strftime('%s',’now’),'localtime', 'unixepoch')

This
This query uses the function datetime to convert the integer result from the strftime function, which is time in Universal Coordinated Time (UTC). So to set it to the system time the ‘localtime’ modificator is used. The result of this reverting function is again in the human readable format – YYYY-MM-DD HH:MM:SS.

This are the steps that could be used, to emulate a date and time class in SQLite, which could be a great miss, if we want to use our database to store time information – a very frequent practice.

This Is the Perfect Solution for Stopping Spam [Comic]

admin — Tue, 24 May 2011 09:22:20 +0000

A nice comic:

This Is the Perfect Solution for Stopping Spam [Comic]

How to Find the First image In WordPress Post or Page

baobab — Sun, 15 May 2011 15:30:04 +0000

You need to add icons to your search results, archives or simply to enable the Facebook Open Graph protocol on your blog site. This task can be accomplished by extracting the URL of the first image, used in post. If you follow certain conventions, this can always be the post or page thumbnail. I have seen many solutions to this relatively simple problem. Unfortunately most of them are incorrect. Here is the right PHP code to get the first image URL from the post content.

post_content, $matches)) {
              return NULL;
          }
          return $matches[2];
    }

    // ...........

}

?>

The core of this technique is the regular expression that matches the first image in the post content.
I haven’t used the preg_match_all function, but preg_match, because I need only the first matching tag.

WordPress plugin: Facebook Like Button and Open Graph For Dummies

baobab — Wed, 11 May 2011 17:51:14 +0000

There are many WordPress plugins that can add the Facebook button to your site. With this plugin you can not only add Like button. You can use different methods, customize the look and feel and enable the Facebook Open Graph protocol support.

Add Facebook Like button to the beginning or ending of a post or page.
Add Facebook Like button to the beginning or ending of the post excerpt on archive pages.
Enable Open Graph protocol support for your blog.
Advanced users can select among number of options and customize the Open Graph protocol details.
Enable content filter as an alternative to the Open Graph protocol.

You can download the latest version of the plugin here.

= 1.0 =
* OpenGraph: Automatic description – strip new lines and multiple spaces.
* OpenGraph: Automatic description – configurable max description length.
* OpenGraph: Automatic Image: Use configurable default image.
* OpenGraph: Admins tag support.
* OpenGraph: Configuration settings for enable/disable OpenGraph protocol support.

= 0.2=
* OpenGraph: Automatic Image: Use first image from post
* OpenGraph: Automatic description – Use “more” for description
* OpenGraph: Automatic description – Generate automatic description, rounded to whole words with about 200 chars length.
* OpenGprah: Automatic description show elipsis if too long.

= 0.1 =
* OpenGraph protocol support
* Setting: Disable all the Facebook Like buttons, automatically added by the plugin
* Ability to automatically add Facebook Like button to Pages
* Ability to automatically add Facebook Like button to Posts

FAQ: Facebook Import Comments to WordPress plugin

baobab — Sat, 07 May 2011 13:52:43 +0000

Frequently Asked Questions for Facebook Import Comments to WordPress plugin

Q. I have some ideas about the plugin. What to do?

A. Great! The plugin is distributed under the GPL license. Everyone can contribute to it. There are many types of contributions. For example:
* comments to existing features
* suggestions for new features
* ideas
* translations in different human languages
* direct code contribution

If you have critiques, please share your opinion with me. I would be glad to here your opinion. Maybe I am wrong, or maybe you. Who knows? Let’s make the world a better place – together.

Q. What happens if a Facebook user removes its comment for my blog post? What action I should take in this case?

A. Since version 1.1 of the plugin Import Mode control setting allows you to specify the plugin’s behavior in this case. By default when user removes a comment from facebook, it is also removed from the blog comment’s list. You can change this behavior by using the “Append new” option.

Q. Is the plugin aligned with the Facebook policies?

A. The plugin is aligned with all known Facebook policies and respects user rights. If you think there are some issues with Facebook policies and user rights, I would be glad to hear about them and introduce necessary changes.
In addition some unique plugin features might be useful in this direction:
* “Delete All Imported Facebook Comments”
* Import Mode setting

Q. Can I separate comments comming from WordPress and from Facebook comments social plugin.

A. Yes, you modify your theme to visually and physically separate both types of comments. The plugin stores special value in the “comment_agent” database field which begins with “facebook-seo-comments”. You can use this fact to modify behavior and visual appearance.

Q. Why the plugin stores the comments into the WordPress database?

A. There are three reasons
* The most important reason is performance. The WordPress database is used to cache Facebook API requests. The result is significant reduce in Facebook engine hits and reduced website traffic.
* Improved user experience.
* Seamless integration for comments posted through Facebook comments social plugin and WordPress comment features.

Facebook Import Comments to WordPress plugin

baobab — Fri, 06 May 2011 05:34:57 +0000

Many sites are using the popular Facebook Comments Social Plugin. The Facebook Import Comments WordPress plugin allows comments generated by the blog visitors to be imported as WordPress comments.

Some visitors prefer to post comments to Facebook Social Plugin as these comments are becoming part of their social activity and are displayed on their wall.

Other visitors prefer not to use Facebook comments. They would like to post their comments to your WordPress blog.

The Facebook Import Comments combines both type of plugins and makes them part of your WordPress blog.

Search Engine Optimization (SEO) benefits should also be considered. Your site will be more dynamic and more attractive for spiders. As a result it will rate higher in search engine results. According to Facebook SEO (Search Engine Optimization) community is the reason for extending the Facebook Social Plugin to be extended to provide an interface for retrieving the comments.

Author: Ivan Georgiev
Download: Download From WordPress.org

See also:
* The Frequently Asked Questions page.

Changelog
= 1.1 =
* New Feature: Import Mode which allows "append new" and "append new and delete missing" synchronization modes.
* Workaround: WordPress uses global variable $id. In some themes and plugins this variable is overwritten and the function get_the_ID() returns incorrect result.
* Changed default language settings: "Retrieve blog locale = No", "Retrieve additional locales = ''". Facebook fixed their API so locale parameter is not anymore required when querying the Facebook comments.

= 1.0 =
* Language options for Facebook connection.
* Protect plugin directory from browsing.

= 0.2.1 =
* Description changed to more distinguishable.

= 0.2 =
* Refresh Interval to reduce bandwidth consumption.
* Administrative interface
* Refresh Interval can be changed through the administrative interface.
* All imported comments can be removed through the administrative interface.
* The administrative interface displays the number of currently imported comments.

Oracle PL/SQL Collections and Associative Arrays

baobab — Thu, 10 Dec 2009 13:56:07 +0000

Associative Arrays

DECLARE
  TYPE population_type IS TABLE OF NUMBER INDEX BY VARCHAR2(64);
  country_population population_type;
  continent_population population_type;
  howmany NUMBER;
  which VARCHAR2(64);
 
BEGIN
  country_population('Greenland') := 100000;
  country_population('Iceland') := 750000;
  howmany := country_population('Greenland');
 
  continent_population('Australia') := 30000000;
  continent_population('Antarctica') := 1000; -- Creates new entry
  continent_population('Antarctica') := 1001; -- Replaces previous value
  dbms_output.put_line('Count: ' || continent_population.count);
 
  which := continent_population.FIRST; -- Returns 'Antarctica'
 
-- as that comes first alphabetically.
  which := continent_population.LAST; -- Returns 'Australia'
  howmany := continent_population(continent_population.LAST);
-- Returns the value corresponding to the last key, in this
-- case the population of Australia.
 
  -- Traverse Continents Associative Array
  dbms_output.put_line('Elements in continent_population: ' || continent_population.count);
  which := continent_population.FIRST;
  WHILE which IS NOT NULL LOOP
    dbms_output.put_line(which || ': ' || continent_population(which));
    which := continent_population.NEXT(which);
  END LOOP;
  -- Outputs:
  --   Count: 2
  --   Elements in continent_population: 2
  --   Antarctica: 1001
  --   Australia: 30000000
 
END;

Extend Oracle PL/SQL Collection

DECLARE
  TYPE CourseList IS TABLE OF VARCHAR2(10);
  courses CourseList := CourseList();
BEGIN
  dbms_output.put_line('Initial count= ' || courses.count ||
                       ', first= ' || courses.first ||
                       ', last= ' || courses.last ||
                       '');
  courses.extend(5);
  dbms_output.put_line('After extend(5) count= ' || courses.count ||
                       ', first= ' || courses.first ||
                       ', last= ' || courses.last ||
                       '');
  dbms_output.put_line('After extend(5) count: ' || courses.count);
 
END;

Initial count= 0, first= , last=
After extend(5) count= 5, first= 1, last= 5
After extend(5) count: 5

Oracle Database Multitable INSERT SQL

baobab — Thu, 10 Dec 2009 09:30:56 +0000

Multitable INSERT SQL can insert simultaneously into more than one tables. You can also specify optional conditions which determine which values are inserted into which tables.

SELECT * FROM sales_input_table;
 
PRODUCT_ID CUSTOMER_ID WEEKLY_ST  SALES_SUN  SALES_MON  SALES_TUE  SALES_WED SALES_THU  SALES_FRI  SALES_SAT
---------- ----------- --------- ---------- ---------- ---------- -------------------- ---------- ----------
       111         222 01-OCT-00        100        200        300        400       500        600        700
       222         333 08-OCT-00        200        300        400        500       600        700        800
       333         444 15-OCT-00        300        400        500        600       700        800        900

The multitable insert statement looks like this:

INSERT ALL
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date, sales_sun)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+1, sales_mon)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+2, sales_tue)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+3, sales_wed)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+4, sales_thu)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+5, sales_fri)
      INTO sales (prod_id, cust_id, time_id, amount)
      VALUES (product_id, customer_id, weekly_start_date+6, sales_sat)
   SELECT product_id, customer_id, weekly_start_date, sales_sun,
      sales_mon, sales_tue, sales_wed, sales_thu, sales_fri, sales_sat
      FROM sales_input_table;

Assuming these are the only rows in the sales table, the contents now look like this:

SELECT * FROM sales
   ORDER BY prod_id, cust_id, time_id;
 
   PROD_ID    CUST_ID TIME_ID   C   PROMO_ID QUANTITY_SOLD     AMOUNT       COST
---------- ---------- --------- - ---------- ------------- ---------- ----------
       111        222 01-OCT-00                                   100
       111        222 02-OCT-00                                   200
       111        222 03-OCT-00                                   300
       111        222 04-OCT-00                                   400
       111        222 05-OCT-00                                   500
       111        222 06-OCT-00                                   600
       111        222 07-OCT-00                                   700
       222        333 08-OCT-00                                   200
       222        333 09-OCT-00                                   300
       222        333 10-OCT-00                                   400
       222        333 11-OCT-00                                   500
       222        333 12-OCT-00                                   600
       222        333 13-OCT-00                                   700
       222        333 14-OCT-00                                   800
       333        444 15-OCT-00                                   300
       333        444 16-OCT-00                                   400
       333        444 17-OCT-00                                   500
       333        444 18-OCT-00                                   600
       333        444 19-OCT-00                                   700
       333        444 20-OCT-00                                   800
       333        444 21-OCT-00                                   900

The next examples insert into multiple tables. Suppose you want to provide to sales representatives some information on orders of various sizes. The following example creates tables for small, medium, large, and special orders and populates those tables with data from the sample table oe.orders:

CREATE TABLE small_orders
   (order_id       NUMBER(12)   NOT NULL,
    customer_id    NUMBER(6)    NOT NULL,
    order_total    NUMBER(8,2),
    sales_rep_id   NUMBER(6)
   );

CREATE TABLE medium_orders AS SELECT * FROM small_orders;

CREATE TABLE large_orders AS SELECT * FROM small_orders;

CREATE TABLE special_orders
   (order_id       NUMBER(12)    NOT NULL,
    customer_id    NUMBER(6)     NOT NULL,
    order_total    NUMBER(8,2),
    sales_rep_id   NUMBER(6),
    credit_limit   NUMBER(9,2),
    cust_email     VARCHAR2(30)
   );

The first multitable insert populates only the tables for small, medium, and large orders:

INSERT ALL
   WHEN order_total < 1000000 THEN
      INTO small_orders
   WHEN order_total > 1000000 AND order_total < 2000000 THEN
      INTO medium_orders
   WHEN order_total > 2000000 THEN
      INTO large_orders
   SELECT order_id, order_total, sales_rep_id, customer_id
      FROM orders;

You can accomplish the same thing using the ELSE clause in place of the insert into the large_orders table:

INSERT ALL
   WHEN order_total < 100000 THEN
      INTO small_orders
   WHEN order_total > 100000 AND order_total < 200000 THEN
      INTO medium_orders
   ELSE
      INTO large_orders
   SELECT order_id, order_total, sales_rep_id, customer_id
      FROM orders;
<pre>
 
The next example inserts INTO the small, medium, AND large TABLES, AS IN the preceding example, AND also puts orders greater than 2,900,000 INTO the special_orders TABLE. This TABLE also shows how TO USE COLUMN aliases TO simplify the statement:
 
<pre lang="sql">
INSERT ALL
   WHEN ottl < 100000 THEN
      INTO small_orders
         VALUES(oid, ottl, sid, cid)
   WHEN ottl > 100000 AND ottl < 200000 THEN
      INTO medium_orders 
         VALUES(oid, ottl, sid, cid)
   WHEN ottl > 200000 THEN
      INTO large_orders
         VALUES(oid, ottl, sid, cid)
   WHEN ottl > 290000 THEN
      INTO special_orders
   SELECT o.order_id oid, o.customer_id cid, o.order_total ottl,
      o.sales_rep_id sid, c.credit_limit cl, c.cust_email cem
      FROM orders o, customers c
      WHERE o.customer_id = c.customer_id;

Finally, the next example uses the FIRST clause to put orders greater than 2,900,000 into the special_orders table and exclude those orders from the large_orders table:

INSERT FIRST
   WHEN ottl < 100000 THEN
      INTO small_orders
         VALUES(oid, ottl, sid, cid)
   WHEN ottl > 100000 AND ottl < 200000 THEN
      INTO medium_orders
         VALUES(oid, ottl, sid, cid)
   WHEN ottl > 290000 THEN
      INTO special_orders
   WHEN ottl > 200000 THEN
      INTO large_orders
         VALUES(oid, ottl, sid, cid)
   SELECT o.order_id oid, o.customer_id cid, o.order_total ottl,
      o.sales_rep_id sid, c.credit_limit cl, c.cust_email cem
      FROM orders o, customers c
      WHERE o.customer_id = c.customer_id;

Oracle Multi-table Insert Syntax


INSERT [hint]
   {
      ALL insert_into_clause [values_clause] [error_logging_clause]
            [insert_into_clause [values_clause] [error_logging_clause]]...
      |
      conditional_insert_clause
   }

conditional_insert_clause ::=
   [ALL | FIRST]
   WHEN condition
      THEN
	     insert_into_clause
            [ values_clause ]
            [ error_logging_clause ]
         [ insert_into_clause
            [ values_clause ]
            [ error_logging_clause ]
         ]...
   [ WHEN condition
      THEN
	     insert_into_clause
            [ values_clause ]
            [ error_logging_clause ]
         [ insert_into_clause
            [ values_clause ]
            [ error_logging_clause ]
         ]...
   ]...

   [ ELSE insert_into_clause
      [ values_clause ]
         [ error_logging_clause ]
      [ insert_into_clause
         [ values_clause ]
         [ error_logging_clause ]
      ]...
   ]

insert_into_clause :=
   INTO dml_table_expression_clause [ t_alias ]
      [ (column [, column ]...) ]

values_clause :=
   VALUES ({ expr | DEFAULT }
      [, { expr | DEFAULT } ]...
   )

Find SQL Executed by a Session – Oracle

baobab — Tue, 08 Dec 2009 13:32:07 +0000

The following SQL shows the SQL text for the SQL being executed by a session.

SELECT s.sid,
       q.sql_text
  FROM v$sqltext q
       JOIN v$session s ON q.address = s.sql_address
 WHERE s.sid = &sid
 ORDER BY piece;

Show the Longest 10 Active User Sessions

baobab — Mon, 07 Dec 2009 13:34:54 +0000

The following SQL can be used by Oracle Database Administrator (DBA) to retrieve information about the currently active sessions with longest execution. The SQL statement is designed to run with SQL*Plus.

To show a list with top current sessions with longest acivity execute in SQL*Plus:

/*
  longest10active.sqlplus.sql
  shows the top 10 active sessions with longest execution activity
  execute in SQL*Plus
*/
col osuser format a10 trunc
col LastCallET format 99,999
col sid format 9999
col spid formar 999999
col username format a10 trunc
col uprogram format a25 trunc
col machine format a10 trunc
SET linesize 132
SET verify off
 
SELECT * FROM (
   SELECT TO_CHAR(s.logon_time, 'mm/dd hh:mi:ssAM') loggedon,
          s.sid, s.STATUS,
          floor(last_call_et/60) "LastCallET",
          s.username, s.osuser,
          p.spid, s.module || ' - ' || s.program uprogram,
          s.machine, s.sql_hash_value
     FROM v$session s, v$process p
    WHERE p.addr = s.paddr
          AND s.type = 'USER'
          AND module IS NOT NULL
          AND s.STATUS = 'ACTIVE'
    ORDER BY 4 DESC)
WHERE ROWNUM < 11;

If you want the execute the statement in different tool, you can remove the formatting clauses:

/*
  longest10active.sql
  shows the top 10 active sessions with longest execution activity
*/
SELECT * FROM (
   SELECT TO_CHAR(s.logon_time, 'mm/dd hh:mi:ssAM') loggedon,
          s.sid, s.STATUS,
          floor(last_call_et/60) "LastCallET",
          s.username, s.osuser,
          p.spid, s.module || ' - ' || s.program uprogram,
          s.machine, s.sql_hash_value
     FROM v$session s, v$process p
    WHERE p.addr = s.paddr
          AND s.type = 'USER'
          AND module IS NOT NULL
          AND s.STATUS = 'ACTIVE'
    ORDER BY 4 DESC)
WHERE ROWNUM < 11;

References

Oracle Applications World: Show the top 10 longest-active user sessions