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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...
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...
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...
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...
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...
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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How can I select multiple columns from a subquery (in SQL Server) that should have one record (selec
...00-1-4' AND '2010-1-4'
, assuming that b.id is a PRIMARY KEY on B
In MS SQL 2005 and higher you may use this syntax:
SELECT SalesOrderID, Foo
FROM (
SELECT A.SalesOrderId, B.Foo,
ROW_NUMBER() OVER (PARTITION BY B.SalesOrderId ORDER BY B.whatever) AS rn
FROM A
JOIN B ON B.SalesOrde...
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...
Nginx url重写rewrite实例详解 - 更多技术 - 清泛网移动版 - 专注C/C++及内核技术
...inx_url_rewrite在nginx中实现url重写，学习rewrite的具体用法，包括301重定向的内容等，希望对大家有所帮助。nginx rewrite 实现二级域名跳转
当访问http://www.jbyuan.com跳转到http://www.jbyuan.com/nvxingjiankang/
方法一：
这种方法浏览器地址会...
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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