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Multiple INSERT statements vs. single INSERT with multiple VALUES
...irely of duplicate rows and neither affects the order of the output of the table of the constants (and as you are inserting into a heap time spent sorting would be pointless anyway even if it did).
Moreover if a clustered index is added to the table the plan still shows an explicit sort step so it...
Array to String PHP?
...e a DB is so you can accomplish work like this trivially. You don't need a table to store arrays, you need a table that you can represent as an array.
Example:
id | word
1 | Sports
2 | Festivals
3 | Classes
4 | Other
You would simply select the data from the table with SQL, rather than have ...
Transitions on the CSS display property
...es up space, and is still rendered inline or as a block or block-inline or table or whatever the display element tells it to render as, and takes up space accordingly.
Other elements do not automatically move to occupy that space. The hidden element just doesn’t render its actual pixels to the out...
Hash and salt passwords in C#
...i Technically, yes, but having a unique salt for each user renders Rainbow Tables (generally accepted as the most efficient way to crack hashed passwords) practically useless. This is a quick oveview gives a in-depth but not overwhelming overview of how to store passwords securely, and why/how it al...
How to specify a multi-line shell variable?
...
simply insert new line where necessary
sql="
SELECT c1, c2
from Table1, Table2
where ...
"
shell will be looking for the closing quotation mark
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Filter data.frame rows by a logical condition
...
we can use data.table library
library(data.table)
expr <- data.table(expr)
expr[cell_type == "hesc"]
expr[cell_type %in% c("hesc","fibroblast")]
or filter using %like% operator for pattern matching
expr[cell_type %like% "hesc...
What happens when a computer program runs?
...me systems)
+---------+
| text | program code, this is the actual executable code that is running.
+---------+
This is the general process address space on many common virtual-memory systems. The "hole" is the size of your total memory, minus the space taken up by all the other areas; this gi...
How to change the output color of echo in Linux
...he corresponding tput command is listed in the Cap-name column of the huge table that starts at line 81.)
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MySQL and GROUP_CONCAT() maximum length
...T SESSION group_concat_max_len = 1000000;
select group_concat(column) from table group by column
You can do this even in sharing hosting, but when you use an other session, you need to repeat the SET SESSION command.
share...
Convert int to char in java
...nt out the char with ascii value 1 (start-of-heading char, which isn't printable).
int a = '1';
char b = (char) a;
System.out.println(b);
will print out the char with ascii value 49 (one corresponding to '1')
If you want to convert a digit (0-9), you can add 48 to it and cast, or something like ...