I have a table with several columns. Sometimes some of these column fields may be empty (ie. I won't use them in some cases). My questions: Would it be smart to set them to NULL in phpmyadmin? What does the "NULL" property actually do? Would I gain anything at all by setting them to NULL? Is it possible to use a NULL field the same w...
I understand how to design a database schema that has simple one-to-many relationships between its tables. I would like to know what the convention or best practice is for designating one particular relationship in that set as the primary one. For instance, one Person has many CreditCards. I know how to model that. How would I designate ...
Hi, I'm working with C# .Net and ms-access database. I have the following SQL query: `Select ... Like "%<aaa>%"+prmPhrase+"%</aaa>%"` The query is looking for a phrase inside a database field which contains xml data. the query works very quickly, but it returns a lot of false results. I can't search only the exact phrase becau...
Assume a database consisting of 1 GB of data and 1 GB of index data. To minimize disk IO and hence maximize performance I want to allocate memory to MySQL so that the entire dataset including indexes can be kept in RAM (assume that the machine has RAM in abundance). The InnoDB parameter innodb_buffer_pool_size is used to specify the si...
Some people have approached me lately about creating a business app for them (I'm a computer tech student specializing in programming, with a bit of experience in systems and driver programming) and it does sound simple, but I don't really have much of an idea how or where to start. It should be a small-ish app with a database backend. ...
I'm trying to get an ordered list of rows out of my MYSQL database table based upon an integer value 'place'. SELECT * FROM mytable ORDER BY place; This works okay, except that all rows with value place=0 should appear at the end of the table. So if my table is: name place ---- ----- John 1 Do 2 Eric 0 Pete 2 it should become: ...
What is the difference between graph-based databases (http://neo4j.org/) and object-oriented databases (http://www.db4o.com/)? ...
Pleaseeee if you guys can help me or point me on the right direction, I would really appreciate. I am saving some data the user inputs into a data file using SQLITE, I am saving date, time, reading, and a note, as the following: //Create a Reading Object Readings *readingObj = [[Readings alloc] initWithPrimaryKey:0]; readingObj.date = ...
I am trying to figure out how one would start the setup of a small CMS. I have the groundwork built, but the step of creating the database tables in mysql, should this all be done at once in a install.php file? Is there a preferred method for creating many tables at once, even if I don't need to insert data into them at this time? ...
Hi I have multiple databases need to back up daily. Currently, I am using cronjob to set a batch file to back it up. Here are my situation, I have about 10 databases need to backup, 3 of them are growing pretty fast, let me show you the current DB size: DB1 = 35 mb DB2 = 10 mb DB3 = 9 mb the rest: DBx = 5 mb My batch file code is: ...
I am getting the error: "The Network Adapter could not establish the connection" from a web application deployed in Oracle Application Server 10g. The database is local, so there shouldn't be any connection issues. First test: I can connect to the DB no problem from SQL plus, run queries, etc. Second test: I can connect to the database...
Hi, I have this question for quite a long time... I have seen many discussions about granting role based access for Databases... But with respect to asp.net web apps... The web app is any way going to connect to the database, with the ID specified in connection string, irrespective of the user connected to the application... (except f...
Sir, Please give me an example showing how to cluster the below data using Agglomerative Clustering by finding Manhattan distance.If possible could you please send me the program code (or algorithm)in java to cluster the below data using average Agglomerative method..Or is their any free tool available to cluster this data using Averag...
Hello all. I have a problem in access. I have an access db with some tables, and I cant read the data stored in that and the characters are some squares. I tried many fonts but I can't read it yet. can anybody help me? ...
I have two tables, classified and fordon. classified table: classified_id (PK) etc... fordon table: id (PK) classified_id (FK) I try to use this code: SELECT * FROM classified, fordon WHERE classified.ad_id IN ('$solr_id_arr_imploded') AND classified.classified_id=fordon.classified_id BTW, the array is a set of ad_id:s returned fr...
Hi, I can easily log last modified date, modified by etc. However, I need old and new value to be logged too. In the interceptor, I can fire a select before postflush starts executing to get the value of the current record. Then I can run a diff between this record and the new one to see what changed and log that information as old and ...
Hi all I want Compact a Access DataBase File in C# by Code. please Help me Edited: I USe Microsoft Access 2007 DataBase File ...
I am trying to teach myself how to use SQL, namely mysql. What I am trying to understand is how to deal with many different types of data with in the same table. Say I am building a web application, and I have many different content types (blog item, comment item, files, pages, forms) that I need to store different data fields for each...
Hi, i just wonder how to configure a c3p0 instance in a web-server against a master/slaves configuration of mysql ? it means that one c3p0 instance may make connections to more than one mysql servers at a time. Thank you Lee ...
Hi everyone, sorry if the title is not very clear. I will try to explain now: I have two tables: table A and table B. The relation between them is one (for A table) to many (for B table). So, it's something like master-detail situation. I have a column 'Amount' in table B that is obviously decimal and a column 'TotalAmount' in table A....