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  • mySQL: How many rows in a table before performance is affected?

    - by Industrial
    Hi everybody, Is there a "known limit" for columns & rows in a mySQL table that when passed, it can be safe to say that performance is severely affected? I've think that I had heard that there is a "golden number" that you really dont want to exceed in either columns or rows in a table. - Or is it all about the size of the index and available RAM + CPU on the server? Thanks!

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  • How do i escape reserve names in a column? MySQL/Create Table

    - by acidzombie24
    I am generating tables from classes in .NET and one problem is a class may have a field name key which is a reserved mysql keyword. How do i escape it in a create table statement? (Note: The other problem below is text must be a fixed size to be indexed/unique) create table if not exists misc_info ( id INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL, key TEXT UNIQUE NOT NULL, value TEXT NOT NULL)ENGINE=INNODB;

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  • MySql: Is it reasonable to use 'view' or I would better denormalize my DB?

    - by Budda
    There is 'team_sector' table with following fields: Id, team_id, sect_id, size, level It contains few records for each 'team' entity (referenced with 'team_id' field). Each record represent sector of team's stadium (totally 8 sectors). Now it is necessary to implement few searches: by overall stadium size (SUM(size)); the best quality (SUM(level)/COUNT(*)). I could create query something like this: SELECT TS.team_id, SUM(TS.size) as OverallSize, SUM(TS.Level)/COUNT(TS.Id) AS QualityLevel FROM team_sector GROUP BY team_id ORDER BY OverallSize DESC / ORDER BY QualityLevel DESC But my concern here is that calculation for each team will be done each time on query performed. It is not too big overhead (at least now), but I would like to avoid performance issues later. I see 2 options here. The 1st one is to create 2 additional fields in 'team' table (for example) and store there OverallSize and QualityLevel fields. If information if 'sector' table is changed - update those table too (probably would be good to do that with triggers, as sector table doesn't change too often). The 2nd option is to create a view that will provide required data. The 2nd option seems much easier for me, but I don't have a lot of experience/knowledge of work with views. Q1: What is the best option from your perspective here and why? Probably you could suggest other options? Q2: Can I create view in such way that it will do calculations rarely (at least once per day)? If yes - how? Q3: Is it reasonable to use triggers for such purpose (1st option). P.S. MySql 5.1 is used, overall number of teams is around 1-2 thousand, overall number of records in sector table - overall 6-8 thousand. I understand, those numbers are pretty small, but I would like to implement the best practice here.

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  • Why does this sql statement keep saying it is a boolean and not a parameter? (php/Mysql)

    - by ggfan
    In this statement, I am trying to see if there if the latest posting in the database that has the exact same title, price, city, state, detail. If there is, then it would say to the user that the exact post has been already made; if not then insert the posting into the dbc. (This is one type of check so that users can't accidentally post twice. This may not be the best check, but this statement error is annoying me, so I want it to work :)) Why won't this sql work? I think it's not letting the title=$title and not getting the value in the $title... ERROR: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in postad.php on line 365 //there is a form that users fill out that has title, price, city, etc <form> blah blah </form> //if users click submit, then does all the checks and if all okay, insert to dbc if (isset($_POST['submit'])) { // Grab the pposting data from the POST and gets rid of any funny stuff $title = mysqli_real_escape_string($dbc, trim($_POST['title'])); $price = mysqli_real_escape_string($dbc, trim($_POST['price'])); $city = mysqli_real_escape_string($dbc, trim($_POST['city'])); $state = mysqli_real_escape_string($dbc, trim($_POST['state'])); $detail = mysqli_real_escape_string($dbc, trim($_POST['detail'])); if (!is_numeric($price) && !empty($price)) { echo "<p class='error'>The price can only be numbers. No special characters, etc</p>"; } //Error problem...won't let me set title=$title, detail=$detail, etc. //this statement after all the checks so that none of the variables are empty $query="Select * FROM posting WHERE user_id={$_SESSION['user_id']} AND title=$title AND price=$price AND city=$city AND state=$state AND detail=$detail"; $data = mysqli_query($dbc, $query); if(mysqli_num_rows($data)==1) { echo "You already posted this ad. Most likely caused by refreshing too many times."; } }

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  • Java / MySQL - How to access connection from another class?

    - by Alex
    I'm just getting my head around java (and OOP for that matter), the only thing I am familiar with is MySQL. I need to keep the DB connection open throughout the duration of the application, as well as a server socket. I'm not even sure if they both need separate classes, but here's what I have so far: http://pastebin.com/qzMFFTrY (it wouldn't all go in a code tag) The variable I need is con for line 86.

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  • How should I structure my settings table with mysql?

    - by incrediman
    I want to use MySQL to store a bunch of admin settings - what's the best way to structure the table? Like this? Setting _|_ Value setting1 | a setting2 | b setting3 | c setting4 | d setting5 | e Or like this? |--------|_setting1_|_setting2_|_setting3_|_setting4_|_setting5_| Settings | a | b | c | d | e | Or maybe some other way?

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  • No database selected error in CodeIgniter running on MAMP stack

    - by Apophenia Overload
    First off, does anyone know of a good place to get help with CodeIgniter? The official community forums are somewhat disappointing in terms of getting many responses. I have ci installed on a regular MAMP stack, and I’m working on this tutorial. However, I have only gone through the Created section, and currently I am getting a No database selected error. Model: <?php class submit_model extends Model { function submitForm($school, $district) { $data = array( 'school' => $school, 'district' => $district ); $this->db->insert('your_stats', $data); } } View: <?php $this->load->helper('form'); ?> <?php echo form_open('main'); ?> <p> <?php echo form_input('school'); ?> </p> <p> <?php echo form_input('district'); ?> </p> <p> <?php echo form_submit('submit', 'Submit'); ?> </p> <?php echo form_close(); ?> Controller: <?php class Main extends controller { function index() { // Check if form is submitted if ($this->input->post('submit')) { $school = $this->input->xss_clean($this->input->post('school')); $district = $this->input->xss_clean($this->input->post('district')); $this->load->model('submit_model'); // Add the post $this->submit_model->submitForm($school, $district); } $this->load->view('main_view'); } } database.php $db['default']['hostname'] = "localhost:8889"; $db['default']['username'] = "root"; $db['default']['password'] = "root"; $db['default']['database'] = "stats_test"; $db['default']['dbdriver'] = "mysql"; $db['default']['dbprefix'] = ""; $db['default']['pconnect'] = TRUE; $db['default']['db_debug'] = TRUE; $db['default']['cache_on'] = FALSE; $db['default']['cachedir'] = ""; $db['default']['char_set'] = "utf8"; $db['default']['dbcollat'] = "utf8_general_ci"; config.php $config['base_url'] = "http://localhost:8888/ci/"; ... $config['index_page'] = "index.php"; ... $config['uri_protocol'] = "AUTO"; So, how come it’s giving me this error message? A Database Error Occurred Error Number: 1046 No database selected INSERT INTO `your_stats` (`school`, `district`) VALUES ('TJHSST', 'FairFax') Is there any way for me to test if CodeIgniter can actually detect the mySQL databases I've created with phpMyAdmin in my MAMP stack?

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  • SQL SERVER – Mirroring Configured Without Domain – The server network address TCP://SQLServerName:50

    - by pinaldave
    Regular readers of my blog will be aware of my friend who called me few days ago with very a funny SQL Problem SQL SERVER – SSMS Query Command(s) completed successfully without ANY Results. This time, it did not take long before he called me up with another interesting problem, although the issue he was facing this time was not that interesting and also very specific to him, however, he insisted me to share with all of you. Let us understand his situation at first. My friend is preparing for DBA exam Exam 70-450: PRO: Designing, Optimizing and Maintaining a Database Server Infrastructure using Microsoft SQL Server 2008 and for the same, he was trying to set up replication on his local laptop. He had installed two different instances of SQL Server on his computer and every time when he started the mirroring, it failed with common error message. The server network address “TCP://SQLServer:5023? cannot be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational. (Microsoft SQL Server, Error: 1418) Well, before he contacted me, he searched online and checked my article written on the error in mirroring. However, he tried all the four suggestions, but it did not solve his problem. He called me at a reasonable time of late evening (unlike last time, which was midnight!). I even tried all the seven different suggestions myself, as previously proposed in my article; however, none of them worked. While looking at closely at services, I noticed something very simple. He was running all the instances on ‘Network Services’. In fact, his computer was a stand-alone computer. There was no network at all. Also, there was no domain or any other advance network concepts implemented. I just changed services from ‘Network Services’ to ‘Local System’ as his SQL Server was running on his local system and there were no network services. This prompted to restart the services. As this was not the production server and his development machine, we restarted the services on the laptop (do not restart services on production server without proper planning). After changing the ‘services log on’ account to localsystem, when he attempted to reconfigure the mirroring it worked right away. As usually in production server, proper domains are configured and advance network concepts are implemented I had never faced this type of problem earlier. My friend insisted to post this solution to his situation, wherein there was no domain configured and setting up mirroring was throwing an error. According to him, this is bound to help people, like him, who are preparing for certification using single system. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Certifications, SQL Mirroring

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  • SQL SERVER – World Shapefile Download and Upload to Database – Spatial Database

    - by pinaldave
    During my recent, training I was asked by a student if I know a place where he can download spatial files for all the countries around the world, as well as if there is a way to upload shape files to a database. Here is a quick tutorial for it. VDS Technologies has all the spatial files for every location for free. You can download the spatial file from here. If you cannot find the spatial file you are looking for, please leave a comment here, and I will send you the necessary details. Unzip the file to a folder and it will have the following content. Then, download Shape2SQL tool from SharpGIS. This is one of the best tools available to convert shapefiles to SQL tables. Afterwards, run the .exe file. When the file is run for the first time, it will ask for the database properties. Provide your database details. Select the appropriate shape files and the tool will fill up the essential details automatically. If you do not want to create the index on the column, uncheck the box beside it. The screenshot below is simply explains the procedure. You also have to be careful regarding your data, whether that is GEOMETRY or GEOGRAPHY. In this example,  it is GEOMETRY data. Click “Upload to Database”. It will show you the uploading process. Once the shape file is uploaded, close the application and open SQL Server Management Studio (SSMS). Run the following code in SSMS Query Editor. USE Spatial GO SELECT * FROM dbo.world GO This will show the complete map of world after you click on Spatial Results in Spatial Tab. In Spatial Results Set, the Zoom feature is available. From the Select label column, choose the country name in order to show the country name overlaying the country borders. Let me know if this tutorial is helpful enough. I am planning to write a few more posts about this later. Note: Please note that the images displayed here do not reflect the original political boundaries. These data are pretty old and can probably draw incorrect maps as well. I have personally spotted several parts of the map where some countries are located a little bit inaccurately. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Spatial, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQL SERVER – How to See Active SQL Server Connections For Database

    - by Pinal Dave
    Another question received via email - “How do I I know which user is connected to my database with how many connection?” Here is the script which will give us answer to the question. SELECT DB_NAME(dbid) AS DBName, COUNT(dbid) AS NumberOfConnections, loginame FROM    sys.sysprocesses GROUP BY dbid, loginame ORDER BY DB_NAME(dbid) Here is the resultset: Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQLAuthority News – Microsoft SQL Server Protocol Documentation Download

    - by pinaldave
    The Microsoft SQL Server protocol documentation provides detailed technical specifications for Microsoft proprietary protocols (including extensions to industry-standard or other published protocols) that are implemented and used in Microsoft SQL Server to interoperate or communicate with Microsoft products. The documentation includes a set of companion overview and reference documents that supplement the technical specifications with conceptual background, overviews of inter-protocol relationships and interactions, and technical reference information. Microsoft SQL Server Protocol Documentation Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – List All the DMV and DMF on Server

    - by pinaldave
    “How many DMVs and DVFs are there in SQL Server 2008?” – this question was asked to me in one of the recent SQL Server Trainings. Answer is very simple: SELECT name, type, type_desc FROM sys.system_objects WHERE name LIKE 'dm_%' ORDER BY name Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • Use XQuery to Access XML in Emacs

    - by Gregory Burd
    There you are working on a multi-MB/GB/TB XML document or set of documents, you want to be able to quickly query the content but you don't want to load the XML into a full-blown XML database, the time spent setting things up is simply too expensive. Why not combine a great open source editor, Emacs, and a great XML XQuery engine, Berkeley DB XML? That is exactly what Donnie Cameron did. Give it a try.

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  • SQL Server – Learning SQL Server Performance: Indexing Basics – Video

    - by pinaldave
    Today I remember one of my older cartoon years ago created for Indexing and Performance. Every single time when Performance is discussed, Indexes are mentioned along with it. In recent times, data and application complexity is continuously growing.  The demand for faster query response, performance, and scalability by organizations is increasing and developers and DBAs need to now write efficient code to achieve this. DBA and Developers A DBA’s role is critical, because a production environment has to run 24×7, hence maintenance, trouble shooting, and quick resolutions are the need of the hour.  The first baby step into any performance tuning exercise in SQL Server involves creating, analysing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behaviour and designing our applications appropriately will make sure the application is performed to its highest potential. Video Learning Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. We decided to build a course which just addresses the practical aspects of the performance. In this course, we explored some of these indexing fundamentals and we elaborated on how SQL Server goes about using indexes.  At the end of this course of you will know the basic structure of indexes, practical insights into implementation, and maintenance tips and tricks revolving around indexes.  Finally, we will introduce SQL Server 2012 column store indexes.  We have refrained from discussing internal storage structure of the indexes but have taken a more practical, demo-oriented approach to explain these core concepts. Course Outline Here are salient topics of the course. We have explained every single concept along with a practical demonstration. Additionally shared our personal scripts along with the same. Introduction Fundamentals of Indexing Index Fundamentals Index Fundamentals – Visual Representation Practical Indexing Implementation Techniques Primary Key Over Indexing Duplicate Index Clustered Index Unique Index Included Columns Filtered Index Disabled Index Index Maintenance and Defragmentation Introduction to Columnstore Index Indexing Practical Performance Tips and Tricks Index and Page Types Index and Non Deterministic Columns Index and SET Values Importance of Clustered Index Effect of Compression and Fillfactor Index and Functions Dynamic Management Views (DMV) – Fillfactor Table Scan, Index Scan and Index Seek Index and Order of Columns Final Checklist: Index and Performance Well, we believe we have done our part, now waiting for your comments and feedback. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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  • SQL SERVER – Change Database Access to Single User Mode Using SSMS

    - by pinaldave
    I have previously written about how using T-SQL Script we can convert the database access to single user mode before backup. I was recently asked if the same can be done using SQL Server Management Studio. Yes! You can do it from database property (Write click on database and select database property) and follow image. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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