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Two single-column indexes vs one two-column index in MySQL?
...a single composite index can speed up several kinds of queries on the same table." - Multiple-Column Indexes
– AlikElzin-kilaka
Sep 9 '18 at 4:46
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UITableView is starting with an offset in iOS 7
I have dragged a plain jane UITableView onto a UIViewController in iOS 7.
20 Answers
2...
AWS MySQL RDS vs AWS DynamoDB [closed]
I've been using MySQL for a fair while now and I'm comfortable with its structure & SQL Queries etc.
4 Answers
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Why is XOR the default way to combine hashes?
... uniform probability distributions.
This can be seen by writing out truth tables:
a | b | a AND b
---+---+--------
0 | 0 | 0
0 | 1 | 0
1 | 0 | 0
1 | 1 | 1
a | b | a OR b
---+---+--------
0 | 0 | 0
0 | 1 | 1
1 | 0 | 1
1 | 1 | 1
a | b | a XOR b
---+---+--------
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How to use count and group by at the same select statement
...atement.
Is there a way for this directly from sql?
For example, having a table with users I want to select the different towns and the total number of users
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log4j logging hierarchy order
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This table might be helpful for you:
Going down the first column, you will see how the log works in each level. i.e for WARN, (FATAL, ERROR and WARN) will be visible. For OFF, nothing will be visible.
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UITableView - change section header color
How can I change color of a section header in UITableView?
31 Answers
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Rake just one migration
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To expand on what Ryan says, if the table has been dropped from the database outside of Rails, rake db:migrate:up VERSION=my_version may do nothing, because the schema_migrations table still says it is has been run. In the same situation rake db:migrate:redo VE...
Rotated elements in CSS that affect their parent's height correctly
...hange it into a clockwise rotation):
.rotation-wrapper-outer {
display: table;
}
.rotation-wrapper-inner {
padding: 50% 0;
height: 0;
}
.element-to-rotate {
display: block;
transform-origin: top left;
/* Note: for a CLOCKWISE rotation, use the commented-out
transform instead of thi...
SQL Server: Difference between PARTITION BY and GROUP BY
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We can take a simple example.
Consider a table named TableA with the following values:
id firstname lastname Mark
-------------------------------------------------------------------
1 arun prasanth ...