sql-optimization | 易学教程

How to get rid of the php wrapping on this sql query

阅读更多关于 How to get rid of the php wrapping on this sql query

问题 I have two tables. One is production table with posts and other is the collection of posts's views. Once a hour, all post views get grouped together and main production table gets updated. And post's views table gets truncated. My objective is to get this function into pure SQL, so I could run it inside database engine as scheduled event. SQL is my weakest point, and I can make it work with SELECT being inside one UPDATE. But if there are two UPDATE queries, then I need some sort of variable.

Optimise multiple OR query

阅读更多关于 Optimise multiple OR query

问题 I have a Database table where I need to validate if a user has entered in the same or partly the same information. Here is what I'm thinking The db layout rec_id (pk), user_id, name, phone, address_1, address_2, zip, company, co_phone, co_address_1, co_address_2, co_zip, billing, bi_phone, bi_address_1, bi_address_2, bi_zip The Query SELECT rec_id FROM tbl_name WHERE user_id = '123456789' OR '1112223333' IN (phone, co_phone, bi_phone) OR 'John Doe' IN (name, business, billing) OR '12345' IN

Can JDBC client execute SET ARITHABORT ON on Microsoft SQL Server 2012?

阅读更多关于 Can JDBC client execute SET ARITHABORT ON on Microsoft SQL Server 2012?

问题 Can I set Microsoft SQL Server 2012 options such as ARITHABORT programmatically from a (remote) Java client that uses Microsoft JDBC Driver 4.0? I've noticed that statement.execute("SET ARITHABORT ON") returns false and the expected effect seems missing, hence the question. 回答1: Can I set Microsoft SQL Server 2012 options such as ARITHABORT programmatically from a (remote) Java client that uses Microsoft JDBC Driver 4.0? It certainly appears so. The code package com.example.sqlservertest;

SQL Server : Issue in exists query replace with joins

阅读更多关于 SQL Server : Issue in exists query replace with joins

问题 I am using the following code to fetch the report. DECLARE @CountryID smallint = 100 DECLARE @UTCTDIM smallint = 330 DECLARE @MarketProfileID smallint = 2 DECLARE @StartDate datetime = '2017-01-01' DECLARE @EndDate datetime = '2017-01-03' DECLARE @CustomerTypeID smallint = 1 SET NOCOUNT ON DECLARE @AirportList TABLE (ID bigint) INSERT INTO @AirportList (ID) SELECT DISTINCT Airport.ID FROM Airport INNER JOIN CityList ON Airport.CityID = CityList.ID INNER JOIN CountryList ON CityList.CountryID

Are Columns Not Selected in SQL Views Executed?

阅读更多关于 Are Columns Not Selected in SQL Views Executed?

问题 I wasn't able to come up with the right keywords to search for the answer for this, so apologies if it was answered already. Consider the following SQL view: CREATE VIEW View1 AS SELECT Column1 ,Column2 ,(SELECT SUM(Column3) FROM Table2 WHERE Table2.ID = Table1.ID) -- Subquery FROM Table1 If I run the following query, will the subquery be executed or does SQL Server optimise the query? SELECT Column1 FROM View1 I'm looking at this from a performance point of view, say, if the view has quite a

SQL Server query optimization?

阅读更多关于 SQL Server query optimization?

问题 I have the following query: SELECT tl.*, d.* FROM TrackerLocations AS tl inner join Trackers t on tl.TrackerId = t.TrackerId inner join Devices d on t.UserId = d.UserId WHERE tl.ReceivedTime = (SELECT MAX(tl2.ReceivedTime) FROM TrackerLocations tl2 WHERE tl2.TrackerId = tl.TrackerId) and tl.ReceivedTime >= DATEADD (MINUTE,-2,GETUTCDATE()) and d.OSType <> 3 and d.Notify = 1 ...and for my surprise, it does not return the results in an acceptable time. First times I runned it in production

SQL Server query optimization?

阅读更多关于 SQL Server query optimization?

I have the following query: SELECT tl.*, d.* FROM TrackerLocations AS tl inner join Trackers t on tl.TrackerId = t.TrackerId inner join Devices d on t.UserId = d.UserId WHERE tl.ReceivedTime = (SELECT MAX(tl2.ReceivedTime) FROM TrackerLocations tl2 WHERE tl2.TrackerId = tl.TrackerId) and tl.ReceivedTime >= DATEADD (MINUTE,-2,GETUTCDATE()) and d.OSType <> 3 and d.Notify = 1 ...and for my surprise, it does not return the results in an acceptable time. First times I runned it in production environment, was like 3 seconds of execution. Now, it runs until timeout (inside C# application, 30 seconds)

How do I select a random record efficiently in MySQL?

阅读更多关于 How do I select a random record efficiently in MySQL?

SQL: How to select one record per day, assuming that each day contain more than 1 value MySQL

阅读更多关于 SQL: How to select one record per day, assuming that each day contain more than 1 value MySQL

I want to select records from '2013-04-01 00:00:00' to 'today' but, each day has lot of value, because they are saving each 15 minutes a value, so I want only the first or last value from each day. Table schema: CREATE TABLE IF NOT EXISTS `value_magnitudes` ( `id` int(11) NOT NULL AUTO_INCREMENT, `value` float DEFAULT NULL, `magnitude_id` int(11) DEFAULT NULL, `sdi_belongs_id` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `reading_date` datetime DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

How do I select a random record efficiently in MySQL?

阅读更多关于 How do I select a random record efficiently in MySQL?