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How to move a model between two Django apps (Django 1.7)
...on(migrations.Migration):
database_operations = [migrations.AlterModelTable('TheModel', 'newapp_themodel')]
state_operations = [migrations.DeleteModel('TheModel')]
operations = [
migrations.SeparateDatabaseAndState(
database_operations=database_operations,
state_...
MYSQL Dump only certain rows
...t dumps everything. How can I get mysqldump to only dump certain rows of a table?
3 Answers
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Why do we always prefer using parameters in SQL statements?
...ommands against your database, including deleting it If they wrote 0; Drop Table employee:
SELECT empSalary from employee where salary = 0; Drop Table employee
The table employee would then be deleted.
In your case, it looks like you're using .NET. Using parameters is as easy as:
C#
string s...
How to drop columns using Rails migration
What's the syntax for dropping a database table column through a Rails migration?
20 Answers
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Reshaping data.frame from wide to long format
I have some trouble to convert my data.frame from a wide table to a long table.
At the moment it looks like this:
9 Answe...
What are the disadvantages of using persistent connection in PDO
...tion die when the script terminates abnormally.
If the dead script locked tables, those tables will remain locked until the connection dies or the next script that gets the connection unlocks the tables itself.
If the dead script was in the middle of a transaction, that can block a multitude of ta...
How do you use script variables in psql?
...nd can then be substituted, for example, as ...
SELECT * FROM :myvariable.table1;
... or ...
SELECT * FROM table1 WHERE :myvariable IS NULL;
edit: As of psql 9.1, variables can be expanded in quotes as in:
\set myvariable value
SELECT * FROM table1 WHERE column1 = :'myvariable';
In olde...
How do you debug MySQL stored procedures?
...current process for debugging stored procedures is very simple. I create a table called "debug" where I insert variable values from the stored procedure as it runs. This allows me to see the value of any variable at a given point in the script, but is there a better way to debug MySQL stored procedu...
What are file descriptors, explained in simple terms?
...file in operating system.
If your process opens 10 files then your Process table will have 10 entries for file descriptors.
Similarly when you open a network socket, it is also represented by an integer and it is called Socket Descriptor.
I hope you understand.
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Database Design for Tagging
...e fine and scale out assuming the right b-tree indexes exist on the middle table
– Adam Musch
Feb 24 '10 at 16:41
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