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How to define two fields “unique” as couple
... How would you handle this say if volume_number could be null? Mysql won't seem to enforce unique in that case.
– Greg
Jun 27 '11 at 17:28
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Only one expression can be specified in the select list when the subquery is not introduced with EXI
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Map and Reduce in .NET
...efinetely not an authoritative source, but I'm pretty sure this comes from SQL. I believe linq was original bought in as a way of making interacting with sql easier in C#. When you're naming functions in that world, aggregate starts to sound a bit more familiar than "reduce" when compared with thing...
Oracle SELECT TOP 10 records
I have an big problem with an SQL Statement in Oracle. I want to select the TOP 10 Records ordered by STORAGE_DB which aren't in a list from an other select statement.
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MySQL Creating tables with Foreign Keys giving errno: 150
I am trying to create a table in MySQL with two foreign keys, which reference the primary keys in 2 other tables, but I am getting an errno: 150 error and it will not create the table.
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How can I rename a database column in a Ruby on Rails migration?
...oing one row at a time. The migration would execute much faster with raw sql statements to update correctly named columns. For example, in the first db migration script, after adding the duplicate column names, execute "Update table_name set correct_name_column_one = old_name_column_one"
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MySQL: Set user variable from result of query
Is it possible to set an user variable based on the result of a query in MySQL?
4 Answers
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What should every programmer know about security? [closed]
...browser ID field as 'user input' but it can just as easily contain, say, a SQL injection.
– Peteris
May 7 '12 at 17:49
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Count the occurrences of DISTINCT values
I am trying to find a MySQL query that will find DISTINCT values in a particular field, count the number of occurrences of that value and then order the results by the count.
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How to combine two or more querysets in a Django view?
...e:
union()
union(*other_qs, all=False)
New in Django 1.11. Uses SQL’s UNION operator to combine the results of two or more QuerySets. For example:
>>> qs1.union(qs2, qs3)
The UNION operator selects only distinct values by default. To allow duplicate values, use the all=T...