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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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How do I use regex in a SQLite query?
...ou need to invoke it slightly differently though, like this: SELECT * FROM table WHERE column regexp("myregexp")
– Tristan
May 30 '14 at 17:16
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Can you get the column names from a SqlDataReader?
...case unless I used quotes around the column name. SELECT id AS "MyId" FROM table;
– styfle
Jul 13 '13 at 0:02
sir its ...
Undefined reference to `pow' and `floor'
... to tell ld runtime linker to include libm.so in the memory map and symbol table of the process, so these symbols get loaded and everything works as expected
– debuti
May 28 '18 at 13:27
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What is the difference between UNION and UNION ALL?
...cted columns need to be of the same data type.
Example: If we have two tables, 1) Employee and 2) Customer
Employee table data:
Customer table data:
UNION Example (It removes all duplicate records):
UNION ALL Example (It just concatenate records, not eliminate duplicates, so it...
UITableView - change section header color
How can I change color of a section header in UITableView?
31 Answers
31
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Converting Storyboard from iPhone to iPad
...e background for everything).
EDIT: It seems the default background for UITableView in the Attributes inspector is rather strange. I had to manually set the background to "Group Table View Background Color" for grouped table views, and "White Color" for non-grouped table views. It then was displa...
What is the best place for storing uploaded images, SQL database or disk file system? [closed]
...ll consume a lot of memory. Also, if you use a storage engine that employs table-locks for writes (ISAM for example), your files table might be locked often depending on the size / rate of files you are storing there.
Regarding security - I usually store the files in a directory that is outside of...
How does grep run so fast?
...looks first
for the final letter of the target string, and uses a lookup table to
tell it how far ahead it can skip in the input whenever it finds a
non-matching character.
GNU grep also unrolls the inner loop of Boyer-Moore, and sets up the
Boyer-Moore delta table entries in such a way...
Order discrete x scale by frequency/value
...
ggplot(mtcars, aes(factor(cyl))) + geom_bar()
# Manual levels
cyl_table <- table(mtcars$cyl)
cyl_levels <- names(cyl_table)[order(cyl_table)]
mtcars$cyl2 <- factor(mtcars$cyl, levels = cyl_levels)
# Just to be clear, the above line is no different than:
# mtcars$cyl2 <- factor(m...