大约有 40,000 项符合查询结果（耗时：0.0514秒） [XML]
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...
How do I split a string so I can access item x?
...-in function STRING_SPLIT that will split a string and return a one-column table result which you can use in a SELECT statement or elsewhere.
– qJake
Apr 3 '17 at 20:24
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When and why are database joins expensive?
...nality when (if) they set up indexes.
It is important to understand that table scans (examination of every row in a table in the course of producing a join) are rare in practice. A query optimiser will choose a table scan only when one or more of the following holds.
There are fewer than 200 row...
Best XML parser for Java [closed]
...g parser implementation in a standard way. The code should be much more portable, and when you realise that a specific parser has grown too old, you can replace it with another without changing a line of your code (if you do it correctly).
Basically there are three ways of handling XML in a standar...
MySQL get row position in ORDER BY
With the following MySQL table:
9 Answers
9
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Compare two MySQL databases [closed]
... sets, etc. mysqldump --opt --compact --skip-extended-insert -u user -p db table > file.sql
– zanlok
Mar 6 '12 at 21:53
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How can I make a div not larger than its contents?
... if someone wonders : one can then center the parent of the table by setting "text-align:center" on it's parent and "text-align:left" on it (e.g. <body style="text-align:center"><span style="text-align:left; display:inline-block;"><table>...</table></span>...
Insert multiple rows WITHOUT repeating the “INSERT INTO …” part of the statement?
...
INSERT INTO dbo.MyTable (ID, Name)
SELECT 123, 'Timmy'
UNION ALL
SELECT 124, 'Jonny'
UNION ALL
SELECT 125, 'Sally'
For SQL Server 2008, can do it in one VALUES clause exactly as per the statement in your question (you just need to add a comm...
MySQL indexes - what are the best practices?
...going on.
Broadly speaking, an index imposes an ordering on the rows of a table.
For simplicity's sake, imagine a table is just a big CSV file. Whenever a row is inserted, it's inserted at the end. So the "natural" ordering of the table is just the order in which rows were inserted.
Imagine y...
Does the join order matter in SQL?
... neither predicate can be satisfied by a row in which all columns from one table are NULL, than to say that it's associative as long as the predicates don't involve IS NULL or 'a function that is related to nulls'. One can easily imagine a predicate that satisfies the former description but not the ...