I have created a sample Django application with multiple models within it and populated data.  Now, I need to add a new column to one of the models?  Here are my concerns?   What will happen if I do syncdb after adding a column to the model , will it just alter the table and add the new column? Or will it create a new table after deleting all the columns?   Is there any better way to tackle this issue?
123542
I'm considering using Django for a project I'm starting (fyi, a browser-based game) and one of the features I'm liking the most is using syncdb to automatically create the database tables based on the Django models I define (a feature that I can't seem to find in any other framework). I was already thinking this was too good to be true when I saw this in the :  Syncdb will not alter existing tables syncdb will only create tables for models which have not yet been installed. It will never issue ALTER TABLE statements to match changes made to a model class after installation. Changes to model classes and database schemas often involve some form of ambiguity and, in those cases, Django would have to guess at the correct changes to make. There is a risk that critical data would be lost in the process. If you have made changes to a model and wish to alter the database tables to match, use the sql command to display the new SQL structure and compare that to your existing table schema to work out the changes.  It seems that altering existing tables will have to be done &quot;by hand&quot;. What I would like to know is the best way to do this. Two solutions come to mind:  As the documentation suggests, make the changes manually in the DB; Do a backup of the database, wipe it, create the tables again (with syncdb, since now it's creating the tables from scratch) and import the backed-up data (this might take too long if the database is big)  Any ideas?
8063
I would like to start a new excel spreadsheet, create a column named Column1, and quickly fill in increments, (Column2, Column3 etc) up to Column500. Is there an easy way to do this?   Also is there an easy way to afterwards select all 500 columns and add 10 rows of data to all of them?
6708
I'm having trouble wrapping my head around this.  Right now I have some models that looks kind of like this:   def Review(models.Model)     ...fields...     overall_score = models.FloatField(blank=True)  def Score(models.Model)     review = models.ForeignKey(Review)     question = models.TextField()     grade = models.IntegerField()   A Review is has several "scores", the overall_score is the average of the scores.  When a review or a score is saved, I need to recalculate the overall_score average.  Right now I'm using a overridden save method.  Would there be any benefits to using Django's signal dispatcher?
111160
Practically, I would never store names for customers in a separate table.  But why not?  It's a one to many relationship (a person can have one name but that name can be used by multiple people).  Isn't it proper design to separate one to many relationships over multiple tables, or am I missing something?
27892
I would like to shift data found in a column to a row by Key field. I have a table, within a geodatabase, set up similar to what's below.  KEY_    Value 123     Yellow 123     Blue 456     Red 456     Yellow 789     Green 246     Green 246     Orange   I want to create a table that moves the data in the Value field to rows based on the KEY_ field. The result will look like what's below.  KEY_    Value001    Value002 123     Yellow      Blue 456     Red         Yellow 789     Green 246     Green       Orange   Does anyone have an idea of how this can be done? I tried using the Transpose tool Esri offers but it didn't produce the result I'm looking for. I have basic understanding of Python.
105548
I make a new column in my attribute table and it has a default value (for example 0). I want to (probably using the field calculator) have the result that row 1 has the value 1, row 2=2 and so on, just like a numbered index.  I'd be thankful for a code example for the field calculator (including the use of $rownum (I think I need this for switching to the line)).
12741
When adding NOT NULL columns with a DEFAULT value - does PostgreSQL optimize this operation?  In case the table has n rows, a not-optimized alter-table-add-column would yield n writes of the default value - which could be very painful, obviously. With the optimization the DB would instantaneously create the new column, store just one copy of the default value which would be returned when no non-default value is found for that column in a suitable index data structure.  For example  such an .
81313
I'm starting a new application and looking at using an ORM -- in particular, SQLAlchemy.  Say I've got a column 'foo' in my database and I want to increment it.  In straight sqlite, this is easy:  db = sqlite3.connect('mydata.sqlitedb') cur = db.cursor() cur.execute('update table stuff set foo = foo + 1')   I figured out the SQLAlchemy SQL-builder equivalent:  engine = sqlalchemy.create_engine('sqlite:///mydata.sqlitedb') md = sqlalchemy.MetaData(engine) table = sqlalchemy.Table('stuff', md, autoload=True) upd = table.update(values={table.c.foo:table.c.foo+1}) engine.execute(upd)   This is slightly slower, but there's not much in it.  Here's my best guess for a SQLAlchemy ORM approach:  # snip definition of Stuff class made using declarative_base # snip creation of session object for c in session.query(Stuff):     c.foo = c.foo + 1 session.flush() session.commit()   This does the right thing, but it takes just under fifty times as long as the other two approaches.  I presume that's because it has to bring all the data into memory before it can work with it.  Is there any way to generate the efficient SQL using SQLAlchemy's ORM?  Or using any other python ORM?  Or should I just go back to writing the SQL by hand?
26033
I'm new to drupal and I need some help.  I created a new module with name user_extra. Which create necessery table when Installing the module.  But I also need to insert some database field in 'users_field_data' table ('user_extra_id' and 'user_office')  In baseFieldDefinitions I wrote all necessery database table fields for user_extra table.   public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {     // Standard field, used as a unique if primary index.     $fields['id'] = BaseFieldDefinition::create('integer')         -&gt;setLabel(t('Unit ID'))         -&gt;setDescription(t('The unit ID.'))         -&gt;setReadOnly(TRUE)         -&gt;setSetting('unsigned', TRUE);      $fields['uuid'] = BaseFieldDefinition::create('uuid')         -&gt;setLabel(t('UUID'))         -&gt;setDescription(t('The unit UUID.'))         -&gt;setReadOnly(TRUE);         .         .         .     $fields['user_info'] = BaseFieldDefinition::create('string')         -&gt;setLabel(t('User Info'))         -&gt;setDescription(t("The User Info"))         -&gt;setSetting('max_length', 255)         -&gt;setDisplayOptions('form', array(           'type' =&gt; 'string_textfield',           'weight' =&gt; 10,         ))         -&gt;setDisplayConfigurable('form', TRUE);      return $fields;      }   When I install the module it inserts all values that I define in baseFieldDefinitions.  But I also need to create 'user_extra_id' and 'user_office' in 'users_field_data' table with setDisplayOptions and setDisplayConfigurable options.  This is the commenting that I made in entity file  /**  * @ContentEntityType(  *   id = "user_extra",  *   label = @Translation("user extra"),  *   handlers = {  *     "storage" = "Drupal\user_extra\UserextraStorage",  *     "storage_schema" = "Drupal\user_extra\UserextraStorageSchema",  *     "access" = "Drupal\user_extra\UserextraAccessControlHandler",  *     "list_builder" = "Drupal\user_extra\UserextraListBuilder",  *     "view_builder" = "Drupal\user_extra\UserextraViewBuilder",  *     "views_data" = "Drupal\user_extra\UserextraViewsData",  *     "form" = {  *       "default" = "Drupal\user_extra\Form\UserextraForm",  *       "add" = "Drupal\user_extra\Form\UserextraAddForm",  *       "edit" = "Drupal\user_extra\Form\UserextraEditForm",  *       "delete" = "Drupal\user_extra\Form\UserextraDeleteForm",  *     }  *   },  *   admin_permission = "administer user_extra",  *   base_table = "user_extra",  *   entity_keys = {  *     "id" = "id",  *     "label" = "name",  *     "uuid" = "uuid",  *   },  *   links = {  *     "canonical" = "/admin/user_extra/{user_extra}",  *     "add-form" = "/admin/user_extra/add",  *     "delete-form" = "/admin/user_extra/{user_extra}/delete",  *     "overview-form" = "/admin/user_extra/${user_extra}/overview",  *     "edit-form" = "/admin/user_extra/{user_extra}",  *     "collection" = "/admin/user_extra",  *     "children" = "/admin/user_extra/{user_extra}/children",  *   },  * )  */
14945
I need to add a specific column if it does not exist. I have something like the following, but it always returns false:  IF EXISTS(SELECT *           FROM   INFORMATION_SCHEMA.COLUMNS           WHERE  TABLE_NAME = 'myTableName'                  AND COLUMN_NAME = 'myColumnName')    How can I check if a column exists in a table of the SQL Server database?
99570
I've just been adding an Index to a table in SQL Server 2005 and it got me thinking. What is the difference between creating 1 index and defining multiple columns over having 1 index per column you want to index.  Are there certain reasons why one should be used over the other?  For example  Create NonClustered Index IX_IndexName On TableName (Column1 Asc, Column2 Asc, Column3 Asc)   Versus  Create NonClustered Index IX_IndexName1 On TableName (Column1 Asc)  Create NonClustered Index IX_IndexName2 On TableName (Column2 Asc)  Create NonClustered Index IX_IndexName3 On TableName (Column3 Asc)
95404
I was adding some tags to my favorite tags today and noticed tags being joined together when the page is refreshed.  Steps to reproduce:   Click edit on Favorite Tags Create the first tag and click add [I added django in this case] Add a second tag and click add [I added python in this case] Refresh page  Favorite tags now show previous tags + djangopython   In the edit section, it appears as if the tags are added separately, but when I refresh the page they get joined  OS: MacOSX-10.8  Browser: Chrome, Firefox
91645
I am working on a conceptual model for a database. I have the following entities:  Student (id, name, date of birth, department)  Subject (id, name)   This is a many-to-many relationship, one student may be enrolled in many courses, each course has many students. From what I understand, as I should break this many-to-many relationship by introducing a new into a entity, say 'registered' which allows a one-to-one relationship or one-to-many relationship?  Is this correct design decision?
22519
When I read Django code I often see in models what is called a "slug". I am not quite sure what this is, but I do know it has something to do with URLs. How and when is this slug-thing supposed to be used?   (I have read its definition in .)
92991
I need to move some terms from one vocabulary to another by retaining all their data: translations, aliases, and node references.  Is it acceptable to change its vid column value directly in the database? The terms don't have hierarchy relationships which needs to be handled.
67882
I am using the  and trying to create a table of 4 columns.   I get the error mentioned in the title of the question. I know the standard reasons why this error can occur.   But my question is: Is it possible that the template or .cls file is controlling the maximum number of columns in a table ? If it were, would I get a different error than this?
95244
I'm working on a single player sports game for a year or so and this doubt came up: how should I treat/store big amounts of data, like player names. Let's take an arbitrary number as example: 10000 names, 5000 first names and 5000 surnames. These names would be equally divided between 100 countries, which give us 50 first names and 50 surnames per country. Should I have a local database with these names (or even these countries) considering this data will be needed to generate new players names during the course of the game? Would that introduce limitations, considering I want to make my game moddable by players, as much as possible? These doubts can be extended to other, more complex game entities, such as:  Players - each one with their own face, attributes, team etc... Teams - each one with its own crest, kit, squad etc...  In my previous research about that, the SQLite popped up as a seemingly viable solution. It happens that I have almost no experience with DB's (specially in games) and would like to know if this is a good direction before start to study and try to implement it.