Re: Stored Procedure help

[kitlenv]

maybe try 'order by sort_id desc'?


On Mon, Jul 14, 2014 at 12:42 PM, Don Wieland d...@pointmade.net wrote:

 I am trying to create this stored procedure, but can't understand why my
 editor is chocking on it. Little help please:

 DELIMITER //
 CREATE PROCEDURE `reset_sortid` (IN category INT(11))
 BEGIN
 DECLARE a INT;
 SET a = 0;
 UPDATE
 documents SET sort_id = (a := a + 1)
 WHERE
 document_category = category
 ORDER BY
 sort_id;
 END
 //


 Don Wieland
 d...@pointmade.net
 http://www.pointmade.net
 https://www.facebook.com/pointmade.band





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Re: LIKE sql optimization

[kitlenv]

*read how a index works technically*


On Wed, Feb 12, 2014 at 12:48 PM, Zhigang Zhang zzgang2...@gmail.comwrote:

 I want to know the reason, in my opinion, to scan the smaller index data
 has
 better performance than to scan the whole table data.





 zhigang



   _

 From: Mathieu Desharnais [mailto:mdesharn...@diffusion.cc]
 Sent: Wednesday, February 12, 2014 9:41 AM
 To: Zhigang Zhang; mysql@lists.mysql.com
 Subject: Re: LIKE sql optimization



 Sql database doesn't use index in like statement if it starts with % ..



 like 'abcd%' would work though...



 To use an index you can store your value using reverse function and index
 it
 .. then your like would use the index.



 2014-02-11 20:23 GMT-05:00 Zhigang Zhang zzgang2...@gmail.com:

 For example:



 Select * from T where col like '%abcd';



 The table T is myisam table and we created a index on col.



 As we known, this like sql does not use the index created on col, it
 confuse
 me, why?



 I think in mysiam engine, the index data is smaller, it can use index link
 list to optimize it so as to reduce the disk scan than to the whole table
 scan.



 Thanks.



 Zhigang

Re: Date comparison help

[kitlenv]

Hi Michael,

FYI: I'm using 5.6.13 and your query returns 0 for the third column with my
instance.

Cheers,
Sam


On Wed, Oct 23, 2013 at 2:35 AM, Michael Stroh st...@astroh.org wrote:

 I recently upgraded a local MySQL installation to 5.5.32 and am trying to
 figure out why the following query won't work as expected anymore. I'm just
 trying to compare a set of dates to NOW() but since the upgrade, these
 don't seem to work as expected.

 SELECT
 DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2 DAY),
 NOW(),
 DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2
 DAY)NOW()

 For instance, when I run it on my system, I get 1 for the third column
 even though comparing the two by eye it should be false.

 Cheers,
 Michael