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A migration to add unique constraint to a combination of columns
...o apply unique constraint to a combination of columns. i.e. for a people table, a combination of first_name , last_Name and Dob should be unique.
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ASP.NET MVC - Attaching an entity of type 'MODELNAME' failed because another entity of the same type
...where I was needing to update records in a many to many with a custom join table in a disconnected app. Even with the entity grabbed from the database, I was getting referential errors, etc. I was using "context.Entry(score).State = System.Data.Entity.EntityState.Modified;" but this finally worked...
Data structure: insert, remove, contains, get random element, all at O(1)
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Consider a data structure composed of a hashtable H and an array A. The hashtable keys are the elements in the data structure, and the values are their positions in the array.
insert(value): append the value to array and let i be its index in A. Set H[value]=i.
remov...
Setting DIV width and height in JavaScript
... </div>
<div id="div_register">
<table>
<tr>
<td>
welcome
</td>
</tr>
</table>
</div>
</body>
<...
Sqlite primary key on multiple columns
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According to the documentation, it's
CREATE TABLE something (
column1,
column2,
column3,
PRIMARY KEY (column1, column2)
);
share
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improve this answer
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CUDA incompatible with my gcc version
...l directory and then make symbolic links to the supported gcc version executables. Pass that local directory to nvcc via the --compiler-bindir option, and you should be able to compile CUDA code without affecting the rest of your system.
EDIT:
Note that this question, and answer, pertain to CUDA...
Find difference between timestamps in seconds in PostgreSQL
I have a table in PostgreSQL 8.3 with 2 timestamp columns. I would like to get the difference between these timestamps in seconds. Could you please help me how to get this done?
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How to import load a .sql or .csv file into SQLite?
...'m using SQLite3 API). I've only found documentation for importing/loading tables, not entire databases. Right now, when I type:
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Order data frame rows according to vector with specific order
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Does anyone know a data.table version of this?
– Reilstein
Sep 23 '16 at 17:50
2
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Meaning of Open hashing and Closed hashing
... us the index (aka. address) at which an object will be stored in the hash table is not completely determined by its hash code. Instead, the index may vary depending on what's already in the hash table.
The "closed" in "closed hashing" refers to the fact that we never leave the hash table; every...