大约有 5,904 项符合查询结果（耗时：0.0190秒） [XML]
Django - How to rename a model field using South?
...foo', 'full_name', 'name')
The first argument of db.rename_column is the table name, so it's important to remember how Django creates table names:
Django automatically derives the name of the database table from the name of your model class and the app that contains it. A model's database tabl...
Django-DB-Migrations: cannot ALTER TABLE because it has pending trigger events
...s at the django shell. If you're looking for something more formal and testable, it depends on what versions you're using. If you use south, see: south.readthedocs.org/en/latest/tutorial/part3.html and if you use django's migrations, see the "data migrations" section here: docs.djangoproject.com/e...
SQL update query using joins
I have to update a field with a value which is returned by a join of 3 tables.
11 Answers
...
How can I define a composite primary key in SQL?
...
Just for clarification: a table can have at most one primary key. A primary key consists of one or more columns (from that table). If a primary key consists of two or more columns it is called a composite primary key. It is defined as follows:
CREATE...
What makes a SQL statement sargable?
...sts. It will literally have to evaluate this function for every row of the table. Much better to use:
WHERE myDate >= '01-01-2008' AND myDate < '01-01-2009'
Some other examples:
Bad: Select ... WHERE isNull(FullName,'Ed Jones') = 'Ed Jones'
Fixed: Select ... WHERE ((FullName = 'Ed Jones') ...
Save PL/pgSQL output from PostgreSQL to a CSV file
...rticular directory, for instance, and the filename might have to have a suitable prefix or extension.
Which tables should the user be able to read/write in the database? This would normally be defined by GRANTs in the database, but the function is now running as a superuser, so tables which would no...
MySQL Query GROUP BY day / month / year
... Simple complete example: SELECT count(*), record_date FROM anytable WHERE anytable.anycolumn = 'anycondition' GROUP BY YEAR(record_date), month(record_date); note: record_date is a date type TIMESTAMP
– renedet
Jul 25 '17 at 18:35
...
Example JavaScript code to parse CSV data
...;
var chars = csv.split(''), c = 0, cc = chars.length, start, end, table = [], row;
while (c < cc) {
table.push(row = []);
while (c < cc && '\r' !== chars[c] && '\n' !== chars[c]) {
start = end = c;
if ('"'...
How to do this in Laravel, subquery where in
...>select('paper_type_id')
->from(with(new ProductCategory)->getTable())
->whereIn('category_id', ['223', '15'])
->where('active', 1);
})->get();
share
|
improve this an...
How to delete migration files in Rails 3
... or staging, it's safer to just write another migration that destroys your table or columns.
Another great reference for migrations is: http://guides.rubyonrails.org/migrations.html
share
|
improve...