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How to implement a unique index on two columns in rails
I have a table and I'm trying to add a unique index on two columns. Those columns are also indexed. So my question is if I just can remove the indexes who were just for one column or if I have to use all three indexes:
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Why is the Fibonacci series used in agile planning poker? [closed]
...nd verbal description in the software domain is closer to the one shown in Table 3 than to Saaty’s." And in this table we see that something is called "slightly bigger" if it is 125% of the base size and it is called "bigger", if it is 175% of the base size.
– asmaier
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What is the difference between a database and a data warehouse?
... as Data Warehousing. This records the data from the user for history.
The tables and joins are complex since they are normalized (for RDMS). This is done to reduce redundant data and to save storage space.
Entity – Relational modeling techniques are used for RDMS database design.
Optimized for wr...
Design Pattern for Undo Engine
...e object is needed, you lookup the current definition of the object from a table. The table contains a linked list for each object that contains all the previous versions, along with information regarding which checkpoint they were active for.
Implementing undo/redo is simple: Do your action and es...
source of historical stock data [closed]
...n reverse engineer the following example:
http://ichart.finance.yahoo.com/table.csv?s=YHOO&d=0&e=28&f=2010&g=d&a=3&b=12&c=1996&ignore=.csv
Essentially:
sn = TICKER
a = fromMonth-1
b = fromDay (two digits)
c = fromYear
d = toMonth-1
e = toDay (two digits)
f = toYear...
Dynamic SELECT TOP @var In SQL Server
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SELECT TOP (@count) * FROM SomeTable
This will only work with SQL 2005+
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Still Reachable Leak detected by Valgrind
... reachable" memory can be considered a memory leak: assume you have a hash table where you add pointers to heap allocated memory as value. If you keep inserting new entries on the table, but won't remove and free those you don't need anymore, it can grow indefinitely, leaking heap memory event if th...
Sqlite LIMIT / OFFSET query
... necessarily mean it's in the order you want. The only way to get a predictable order is to use ORDER BY explicitly.
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SQL Server CTE and recursion example
...your question?
--------------------------------------------
-- Synthesise table with non-recursive CTE
--------------------------------------------
;WITH Employee (ID, Name, MgrID) AS
(
SELECT 1, 'Keith', NULL UNION ALL
SELECT 2, 'Josh', 1 UNION ALL
SELECT 3...
Create a custom View by inflating a layout?
...u are using a bit of xml repeatedly. Suppose, for example, that you have a table that you wish to create a table row for each entry in a list. You've set up some xml:
In my_table_row.xml:
<?xml version="1.0" encoding="utf-8"?>
<TableRow xmlns:android="http://schemas.android.com/apk/res/an...