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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
This is a bit of a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...
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Creating an index on a table variable
Can you create an index on a table variable in SQL Server 2000?
3 Answers
3
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MySQL: multiple tables or one table with many columns?
... user has one name and password), then it's probably better to have it one table, since it reduces the number of joins the database will need to do to retrieve results. I think some databases have a limit on the number of columns per table, but I wouldn't worry about it in normal cases, and you can ...
Alter MySQL table to add comments on columns
I have been checking the MySQL Documentation for ALTER TABLE and it does not seem to include a way to add or modify a comment to a column. How can I do this?
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Django: Get list of model fields?
..., blog, shop, etc.)
1) From model link: https://docs.djangoproject.com/en/stable/ref/models/meta/
from posts.model import BlogPost
all_fields = BlogPost._meta.fields
#or
all_fields = BlogPost._meta.get_fields()
Note that:
all_fields=BlogPost._meta.get_fields()
Will also get some relationships, wh...
Is there a way to detect if an image is blurry?
...at representing the blurryness of a given image, you have to work out a suitable metric.
nikie's answer provide such a metric. Convolve the image with a Laplacian kernel:
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1 -4 1
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And use a robust maximum metric on the output to get a number which you can use for thresholding. Try to a...
What's the difference between a temp table and table variable in SQL Server?
In SQL Server 2005, we can create temp tables one of two ways:
12 Answers
12
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How can I list ALL grants a user received?
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If you want more than just direct table grants (e.g., grants via roles, system privileges such as select any table, etc.), here are some additional queries:
System privileges for a user:
SELECT PRIVILEGE
FROM sys.dba_sys_privs
WHERE grantee = <theUser...
What type of hash does WordPress use?
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The WordPress password hasher implements the Portable PHP password hashing framework, which is used in Content Management Systems like WordPress and Drupal.
They used to use MD5 in the older versions, but sadly for me, no more. You can generate hashes using this encrypti...
MySQL InnoDB not releasing disk space after deleting data rows from table
I have one MySQL table using the InnoDB storage engine; it contains about 2M data rows. When I deleted data rows from the table, it did not release allocated disk space. Nor did the size of the ibdata1 file reduce after running the optimize table command.
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