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  • How to save to two tables using one SQLAlchemy model

    - by Oatman
    I have an SQLAlchemy ORM class, linked to MySQL, which works great at saving the data I need down to the underlying table. However, I would like to also save the identical data to a second archive table. Here's some psudocode to try and explain what I mean my_data = Data() #An ORM Class my_data.name = "foo" #This saves just to the 'data' table session.add(my_data) #This will save it to the identical 'backup_data' table my_data_archive = my_data my_data_archive.__tablename__ = 'backup_data' session.add(my_data_archive) #And commits them both session.commit() Just a heads up, I am not interested in mapping a class to a JOIN, as in: http://www.sqlalchemy.org/docs/05/mappers.html#mapping-a-class-against-multiple-tables

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  • Iterating over a database column in Django

    - by curious
    I would like to iterate a calculation over a column of values in a MySQL database. I wondered if Django had any built-in functionality for doing this. Previously, I have just used the following to store each column as a list of tuples with the name table_column: import MySQLdb import sys try: conn = MySQLdb.connect (host = "localhost", user = "user", passwd="passwd", db="db") except MySQLdb.Error, e: print "Error %d: %s" % (e.args[0], e.args[1]) sys.exit (1) cursor = conn.cursor() for table in ['foo', 'bar']: for column in ['foobar1', 'foobar2']: cursor.execute('select %s from %s' % (column, table)) exec "%s_%s = cursor.fetchall()" % (table, column) cursor.close() conn.commit() conn.close() Is there any functionality built into Django to more conveniently iterate through the values of a column in a database table? I'm dealing with millions of rows so speed of execution is important.

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  • MySQL ORDER BY returns things in (apparently) random order !?

    - by Luke H
    The following query: SELECT DISTINCT ClassName FROM SiteTree ORDER BY ClassName is returning things in no apparent order! I get the same result whether I quote column/table names, or use DISTINCT or not, or add ASC or DESC. I assumed the indexes might be broken, or something like this, so tried dropping and recreating. Also tried REPAIR TABLE and CHECK TABLE. The table collation is set to latin1_swedish_ci. All the textual columns are set to use UTF-8 and collation is set to utf8_general_ci What could be causing this?

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  • Fluent NHibernate - Set reference key columns to null

    - by Matt
    Hi, I have a table of Appointments and a table of AppointmentOutcomes. On my Appointments table I have an OutcomeID field which has a foreign key to AppointmentOutcomes. My Fluent NHibernate mappings look as follows; Table("Appointments"); Not.LazyLoad(); Id(c => c.ID).GeneratedBy.Assigned(); Map(c => c.Subject); Map(c => c.StartTime); References(c => c.Outcome, "OutcomeID"); Table("AppointmentOutcomes"); Not.LazyLoad(); Id(c => c.ID).GeneratedBy.Assigned(); Map(c => c.Description); Using NHibernate, if I delete an AppointmentOutcome an exception is thrown because the foreign key is invalid. What I would like to happen is that deleting an AppointmentOutcome would automatically set the OutcomeID of any Appointments that reference the AppointmentOutcome to NULL. Is this possible using Fluent NHibernate?

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  • MySQL - Update the same column twice

    - by uzioriluzan
    Hello, I need to update a column in a mysql table. If I do it in two steps as below, is the column "col" updated twice in the disk ? update table SET col=3*col, col=col+2; or is it written only once as in : update table SET col=3*col+2; Thanks

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  • Creating temporary tables in MySQL Stored Procedure

    - by burntblark
    The following procedure gives me an error when I invoke it using the CALL statement: CREATE DEFINER=`user`@`localhost` PROCEDURE `emp_performance`(id VARCHAR(10)) BEGIN DROP TABLE IF EXISTS performance; CREATE TABLE performance AS SELECT time_in, time_out, day FROM attendance WHERE employee_id = id; END The error says "Unknown table 'performance' ". This is my first time actually using stored procedures and I got my sources from Google. I just cant figure out what I am doing wrong.

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  • nhibernate activerecord lazy collection with custom query

    - by George Polevoy
    What i'm trying to accomplish, is having a temporal soft delete table. table Project(ID int) table ProjectActual(ProjectID int, IsActual bit, ActualAt datetime) Now is it possible to map a collection of actual projects, where project is actual when there is no record in ProjectActual.ProjectID = ID, or the last record sorted by ActualAt descending has IsActual set to 1 (true)?

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  • is it safe to refactor my django models?

    - by Johnd
    My model is similar to this. Is this ok or should I make the common base class abstract? What are the differcenes between this or makeing it abstract and not having an extra table? It seems odd that there is only one primary key now that I have factored stuff out. class Input(models.Model): details = models.CharField(max_length=1000) user = models.ForeignKey(User) pub_date = models.DateTimeField('date published') rating = models.IntegerField() def __unicode__(self): return self.details class Case(Input): title = models.CharField(max_length=200) views = models.IntegerField() class Argument(Input): case = models.ForeignKey(Case) side = models.BooleanField() is this ok to factor stuff out intpu Input? I noticed Cases and Arguments share a primary Key. like this: CREATE TABLE "cases_input" ( "id" integer NOT NULL PRIMARY KEY, "details" varchar(1000) NOT NULL, "user_id" integer NOT NULL REFERENCES "auth_user" ("id"), "pub_date" datetime NOT NULL, "rating" integer NOT NULL ) ; CREATE TABLE "cases_case" ( "input_ptr_id" integer NOT NULL PRIMARY KEY REFERENCES "cases_input" ("id"), "title" varchar(200) NOT NULL, "views" integer NOT NULL ) ; CREATE TABLE "cases_argument" ( "input_ptr_id" integer NOT NULL PRIMARY KEY REFERENCES "cases_input" ("id"), "case_id" integer NOT NULL REFERENCES "cases_case" ("input_ptr_id"), "side" bool NOT NULL )

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  • Updating an integer defined column in a MySQL DB with PHP

    - by Zloy Smiertniy
    I have a table defined like this: create table users ( id int(10), age int(3), name varchar (50) ) I want to use a query to update just age, which is an integer, that comes from an html form. When it arrives to the method that updates it, it comes as a string, so I change it to integer with PHP and try to update the table, but it doesn't work $age = intval($age); $q2 = "UPDATE users SET age='$age' where username like '$username';"; mysql_query($q2,$con);

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  • When using SELECT can you modify the value of a returned field based on other fields?

    - by user570759
    When using MySQL SELECT can you change the value of a returned field based on other fields? For example, if I have this select: SELECT city,state,country FROM table Now if city is empty AND state is empty, I want the value of country to returned empty as well (whether country actually has a value or not). Example table: id | city | state | country ----------------------------- 1 | Here | There | MyCountry 2 | | | YourCountry So with the above table, I want the results for id=1 to return Here,There,MyCountry but the results for id=2 should be empty,empty,empty Thanks

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  • Logic: Best way to sample & count bytes of a 100MB+ file

    - by Jami
    Let's say I have this 170mb file (roughly 180 million bytes). What I need to do is to create a table that lists: all 4096 byte combinations found [column 'bytes'], and the number of times each byte combination appeared in it [column 'occurrences'] Assume two things: I can save data very fast, but I can update my saved data very slow. How should I sample the file and save the needed information? Here're some suggestions that are (extremely) slow: Go through each 4096 byte combinations in the file, save each data, but search the table first for existing combinations and update it's values. this is unbelievably slow Go through each 4096 byte combinations in the file, save until 1 million rows of data in a temporary table. Go through that table and fix the entries (combine repeating byte combinations), then copy to the big table. Repeat going through another 1 million rows of data and repeat the process. this is faster by a bit, but still unbelievably slow This is kind of like taking the statistics of the file. NOTE: I know that sampling the file can generate tons of data (around 22Gb from experience), and I know that any solution posted would take a bit of time to finish. I need the most efficient saving process

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  • Mysql dropping inserts with triggers

    - by user2891127
    Using mysql 5.5. I have two tables. One has a whitelist of hashes. When I insert a new row into the other table, I want to first compare the hash in the insert statement to the whitelist. If it's in the whitelist, I don't want to do the insert (less data to plow through later). The inserts are generated from another program and are text files with sql statements. I've been playing with triggers, and almost have it working: BEGIN IF (select count(md5hash) from whitelist where md5hash=new.md5hash) 0 THEN SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Already Whitelisted'; END IF; END But there's a problem. The Signal throwing up the error stops the import. I want to skip that line, not stop the whole import. Some searching didn't find any way to silently skip the import. My next idea was to create a duplicate table definition, and redirect the insert to that dup table. But the old and new don't seem to apply to table names. Other then adding an ignore column to my table then doing a mass drop based on that column after the import, is there any way to achieve my goal?

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  • I can't able to edit my column name after saving

    - by Midhun M
    I create a new table of employee now I want to edit one of the column name in that table. I can edit but while saving a pop up window asks to save some text file. How may I resolve this? Is it possible to edit without creating a new table? The text file is /* Friday, August 22, 20144:32:53 PM User: Server: MIDHUN\SQLEXPRESS Database: LinQ Application: */ employee

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  • How can I treat a sequence value like a generated key?

    - by Jeff Knecht
    Here is my situation and my constraints: I am using Java 5, JDBC, and DB2 9.5 My database table contains a BIGINT value which represents the primary key. For various reasons that are too complicated to go into here, the way I insert records into the table is by executing an insert against a VIEW; an INSTEAD OF trigger retrieves the NEXT_VAL from a SEQUENCE and performs the INSERT into the target table. I can change the triggers, but I cannot change the underlying table or the general approach of inserting through the view. I want to retrieve the sequence value from JDBC as if it were a generated key. Question: How can I get access to the value pulled from the SEQUENCE. Is there some message I can fire within DB2 to float this sequence value back to the JDBC driver?

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  • how to know on which column,the sequence is applied?

    - by Vineet
    I have to fetch all sequences with their table name along with the column name on which sequence is applied .Some how i managed to fetch table name corresponding to sequence because in my data base sequence is stored with first name as table name from data dictionary(all_sequences and all_tables) . Please let me know how to fetch corresponding column name also if possible!!

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  • SQLite3 and "cascade" SELECTion

    - by SK9
    I have a parent table and a child table related to the parent table by some REFERENCE. Suppose I exec a SELECT statement on the child and that it returns the at least one result. Can I arrange for my search to automatically yield all the content of all related parents with this child too? Or must I always take the reference from the child and put this in a second SELECT statement and exec this myself?

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  • Making a many-to-many relationship using DataRelations object

    - by dotnetdev
    Hi, I have about 200 tables which need to relate to another table in a many-to-many fashion. I have the tables (including the intersection table) ready IN SQL Server. How can I write code using the data relation object to make the relationship? The tables are: PartStatPartName PartsMaterialsIntersection << Materials The materials table needs to have a foreign key from the PartStatPartName table. I tried various approaches using the DataRelation class but the change did not sync to SQL Server, despite being connected and adding the relation, and then calling AcceptChanges() on the dataset. Any guidance much appreciated. I have seen some threads covering the same problem but need an example in code so I can follow the right method. Thanks

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  • How to create reference tables using fluent nhibernate

    - by Akk
    How can i create a 3 table schema from the following model classes. public class Product { public int Id {get; set;} public string Name {get; set;} public IList<Photo> Photos {get; set;} } public class Photo { public int Id {get; set;} public string Path {get; set;} } I want to create the following table structure in the database: Product ------- Id Name ProductPhotos ------------- ProductId (FK Products.Id) PhotoId (FK Photos.Id) Photos ------ Id Path How i can express the above Database Schema using Fluent NHibernate? I could only manage the following the Mapping but this does not get me the 3rd Photo ref table. public class ProductMap : ClassMap<Product> { public CityMap() { Id(x => x.Id); Map(x => x.Name); Table("Products"); HasMany(x => x.Photos).Table("ProductPhotos").KeyColumn("ProductId"); } }

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  • database assignment

    - by eric
    Hi, Given the following table: CREATE TABLE T1 (A INTEGER NOT NULL); CREATE TABLE T3 (A SMALLINT NOT NULL); INSERT T1 VALUES (32768.5); SELECT * FROM T1; INSERT T3 SELECT * FROM T1; SELECT * FROM T3; What is the output of above query? If any error occured please declare the line of it?Explain your answer!

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  • Question on different ways to link tables

    - by dotnetdev
    What is the difference between linking two tables and then the PK is an FK in the other table, but the FK has not got the primary key option (so it does not have the gold key), and having the PK in one table as a PK in another table? Am I right to think that the second option is for a many-to-many relationship? Thanks

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  • C# : Problem in creating diffrent types of columns in a gridview

    - by Royson
    My windows form application has a grid view control with filename as a default column. User should create a column of following types Text, Number, Currency, Combo Box, Check Box, Radio Button ,Date time type (should display DateTimePicker control) and Hyper Link type. After that i want to pass all rows to next screen for further processing. We can create a column of these types in a grid view but how can i store it in a data table so that i can pass it to next screen. Or should i create a column in a data table and then assign data table to grid view by gridview.DataSource = dt; but can we create a these types of columns in a data table. I am so confused!! Please help me to solve this problem. Thanks

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  • SQL update statement to change the value of a field and not replace it

    - by wzzrd
    I'm in the process of migrating some databases. I have this table that has a couple of hundred rows, and has a filename column. To each record in this table, the filename column needs to be altered and part of a path needs to be prepended to the value that is in that field. The table is like: | 1 | filename1 | | 2 | filename2 | and needs to become: | 1 | path/filename1 | | 2 | path/filename2 | I am not an SQL guru, but I know the basics. This eludes me though. Is there a way to do something like: update table set filename = 'path/' + filename where id = 1;

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  • [SQL] Getting the sum of several columns from two tables

    - by romaintaz
    I want to get the sum of several columns from 2 different tables (these tables share the same structure). If I only consider one table, I would write this kind of query: SELECT MONTH_REF, SUM(amount1), SUM(amount2) FROM T_FOO WHERE seller = XXX GROUP BY MONTH_REF; However, I would like to also work with the data from the table T_BAR, and then have a select query that return the following columns: MONTH_REF SUM(T_FOO.amount1) + SUM(T_BAR.amount1) SUM(T_FOO.amount2) + SUM(T_BAR.amount2) everything grouped by the value of MONTH_REF. Note that a record for a given MONTH_REF can be found in one table but not in the other table. In this case, I would like to get the sum of T_FOO.amount1 + 0 (or 0 + T_BAR.amount1). How can I write my SQL query to get this information? For information, my database is Oracle 10g.

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  • continuously fetch data from database using JAVA

    - by deathcaller
    Hi all, I've a scenario where my java program has to continuously communicate with the database table, example my java program has to get the data of my table when new rows are added to it at runtime. There should be continuous communication between my program and database. if the table has 10 rows initially and 2 rows are added by the user, it must detect this and return the rows. My program shouldn't use AJAX and timers. Please Help.

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