Efficient Tables.
I am starting out on a project where I need to store GPS information. The data consists largely of a series of "Points" each consisting of a longitude,latitude and elevation.
On a typical "route" there could be hundreds of points.
My question is how can I efficiently store this information. It does not sound sensible to normalise this and add hundreds of rows to a table for each "route".
Sample data is along the lines of :
- <trkpt lat="54.016942977905273" lon="-1.4903640747070313">
<ele>82.330078125</ele>
<time>2006-09-03T07:35:41Z</time>
</trkpt>
- <trkpt lat="54.016938870772719" lon="-1.490332055836916">
<ele>0</ele>
<time>2006-09-03T07:35:42Z</time>
</trkpt>
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Option 2: SELECT persid FROM person p WHERE (EXISTS(SELECT * FROM perscolor pc WHERE pc.colorid=1 AND p.persid=pc.persid) OR EXISTS(SELECT * FROM perscolor pc WHERE pc.colorid=3 AND p.persid=pc.persid)) AND EXISTS(SELECT * FROM perscolor pc WHERE pc.colorid=2 AND p.persid=pc.persid) AND EXISTS(SELECT * FROM persmaterial pm WHERE pm.materialid=2 AND p.persid=pm.persid) Remarks: *very easy to get from pseudo query to MySQL query but what about performance? Option 3: SELECT p.persid FROM person p, perscolor pc, persmaterial pm WHERE p.persid=pc.persid AND (pc.colorid=1 OR pc.colorid=2 OR pc.colorid=3) AND p.persid=pm.persid AND pm.materialid=2 GROUP BY p.persid HAVING sum(case when pc.colorid in (Ƈ',Ɖ') then 1 else 0 end) >= 1 AND sum(case when pc.colorid=ƈ' then 1 else 0 end)>=1 AND sum(case when pm.materialid=ƈ' then 1 else 0 end)>=1 Remarks: *this option requires the pseudo query to be turned into a product of sums form; again is their a clever way to obtain such a form; Option 4 SELECT DISTINCT pc1.persid FROM perscolor pc1 INNER JOIN perscolor pc2 ON pc1.persid=pc2.persid AND pc2.colorid=2 INNER JOIN persmaterial pm1 ON pc1.persid=pm1.persid AND pm1.materialid=2 LEFT OUTER JOIN perscolor pc3 ON pc1.persid=pc3.persid AND pc3.colorid=1 LEFT OUTER JOIN perscolor pc4 ON pc1.persid=pc4.persid AND pc4.colorid=3 WHERE COALESCE(pc3.persid,pc4.persid) IS NOT NULL Remarks: *this option requires the pseudo query to be turned into a product of sums form Option 5: SELECT p.persid FROM person p, persmaterial pm,perscolor pc1,perscolor pc2,perscolor pc3 WHERE p.persid=pm.persid AND p.persid=pc1.persid AND p.persid=pc2.persid AND p.persid=pc3.persid AND (pc1.colorid=1 OR pc2.colorid=3) AND pc3.colorid=2 AND pm.materialid=2 GROUP BY p.persid Remarks: *very easy to get from pseudo query to MySQL query but what about performance? -- phpMyAdmin SQL Dump -- version 2.6.1 -- http://www.phpmyadmin.net -- -- Host: localhost -- Generation Time: Oct 19, 2006 at 01:13 PM -- Server version: 4.1.9 -- PHP Version: 4.3.10 -- -- Database: `aston` -- -- -------------------------------------------------------- -- -- Table structure for table `color` -- CREATE TABLE `color` ( `colorid` int(11) NOT NULL auto_increment, `color` varchar(30) NOT NULL default '', PRIMARY KEY (`colorid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ; -- -- Dumping data for table `color` -- INSERT INTO `color` VALUES (1, 'red'); INSERT INTO `color` VALUES (2, 'green'); INSERT INTO `color` VALUES (3, 'blue'); INSERT INTO `color` VALUES (4, 'yellow'); -- -------------------------------------------------------- -- -- Table structure for table `material` -- CREATE TABLE `material` ( `materialid` int(11) NOT NULL auto_increment, `material` varchar(30) NOT NULL default '', PRIMARY KEY (`materialid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Dumping data for table `material` -- INSERT INTO `material` VALUES (1, 'wood'); INSERT INTO `material` VALUES (2, 'iron'); -- -------------------------------------------------------- -- -- Table structure for table `perscolor` -- CREATE TABLE `perscolor` ( `perscolorid` int(11) NOT NULL auto_increment, `persid` int(11) NOT NULL default Ɔ', `colorid` int(11) NOT NULL default Ɔ', PRIMARY KEY (`perscolorid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ; -- -- Dumping data for table `perscolor` -- INSERT INTO `perscolor` VALUES (1, 1, 1); INSERT INTO `perscolor` VALUES (2, 1, 2); INSERT INTO `perscolor` VALUES (3, 2, 1); INSERT INTO `perscolor` VALUES (5, 3, 3); INSERT INTO `perscolor` VALUES (6, 3, 2); -- -------------------------------------------------------- -- -- Table structure for table `persmaterial` -- CREATE TABLE `persmaterial` ( `persmatid` int(11) NOT NULL auto_increment, `persid` int(11) NOT NULL default Ɔ', `materialid` int(11) NOT NULL default Ɔ', PRIMARY KEY (`persmatid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ; -- -- Dumping data for table `persmaterial` -- INSERT INTO `persmaterial` VALUES (1, 1, 1); INSERT INTO `persmaterial` VALUES (2, 1, 2); INSERT INTO `persmaterial` VALUES (3, 2, 1); INSERT INTO `persmaterial` VALUES (5, 3, 2); -- -------------------------------------------------------- -- -- Table structure for table `person` -- CREATE TABLE `person` ( `persid` int(11) NOT NULL auto_increment, `name` varchar(30) NOT NULL default '', PRIMARY KEY (`persid`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ; -- -- Dumping data for table `person` -- INSERT INTO `person` VALUES (1, 'john'); INSERT INTO `person` VALUES (2, 'emily'); INSERT INTO `person` VALUES (3, 'liz');
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I need to set up some tables for a bookmarking module that I am making for a CMS. The data contained will be: userID catID catNAME bmName bmURL This will all have to be grouped around the userID as that will vary depending on who is logged in at any given time and I will be running queries like select all where username = 1 and catID = 10 , etc, etc I will also need to be able to insert new categorys (catID) that will reamin unique to each user.Now I would like to know what the best way would be to set up the tables for this - I could do this by trial and error, but I would like to hear an experts advice/opinion.
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MAX() From Two Tables
In the spirit of... SELECT MAX(id) FROM tableOne I'd like to find the MAX(id) of either tableOne or tableTwo, whichever is highest. For example, if tableOne's highest id was 6 and tableTwo's was 9 I'd like to retrieve nine, and vice-versa should tableOne's MAX(id) be greater than tableTwo's. Right now I have two queries followed by a conditional in PHP. It works, it's just not as classy. I've got the gutt feeling that MySQL can do it in one statement.
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Two Tables
I have 2 tables that are maintained independently but contain several columns containing data with the same field names. How do I join one table on top of the other so that I can select from both, As if it were temporarily one table?
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