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What's the best strategy for unit-testing database-driven applications?
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I'm always running tests against an in-memory DB (HSQLDB or Derby) for these reasons:
It makes you think which data to keep in your test DB and why. Just hauling your production DB into a test system translates to "I have no idea what I'm doing or why and if something break...
How to change column datatype in SQL database without losing data
I have SQL Server database and I just realized that I can change the type of one of the columns from int to bool .
11 A...
How to Select Every Row Where Column Value is NOT Distinct
...e or be used in an aggregate function error. Is the only fix - editing the sql_mode?
– Volodymyr Bobyr
Jul 16 at 16:21
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How do I escape double quotes in attributes in an XML String in T-SQL?
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tSql escapes a double quote with another double quote. So if you wanted it to be part of your sql string literal you would do this:
declare @xml xml
set @xml = "<transaction><item value=""hi"" /></transaction...
ActiveRecord.find(array_of_ids), preserving order
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The answer is for mysql only
There is a function in mysql called FIELD()
Here is how you could use it in .find():
>> ids = [100, 1, 6]
=> [100, 1, 6]
>> WordDocument.find(ids).collect(&:id)
=> [1, 6, 100]
>> WordDoc...
SQL Inner-join with 3 tables?
...nthenet.com (my boss recommended it to me, that's how I found it) has good SQL tutorials if you ever have another question and you just want to try and figure it out.
SELECT table1.column1
FROM table1
WHERE table1 > 0 (or whatever you want to specify)
INNER JOIN table1
ON table1.column1 = tabl...
When to Redis? When to MongoDB? [closed]
...licity, much shorter learning curve for developers with traditional DB and SQL experience. However, Redis's non-traditional approach requires more effort to learn, but greater flexibility.
Eg. A cache layer can probably be better implemented in Redis. For more schema-able data, MongoDB is better. ...
Commenting code in Notepad++
...ng the language manually - or - it contains a mix of languages (eg. inline SQL in Python code), the block comment/uncomment will not work.
– Juha Untinen
Apr 22 '16 at 6:50
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ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
... that. One common scenario is that you've tested the update in a tool, say SQL Developer or Toad, and have then tried to run it somewhere else while the first session still holds the lock. So you need to commit/rollback the other session before you can run the update again.
– A...
How can I alter a primary key constraint using SQL syntax?
...ing a column in its primary key constraint. Instead of editing it through SQL Server, I want to put this in a script to add it as part of our update scripts.
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