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creating a random number using MYSQL
...t to a variable and use the variable if you have master slave replication. SET @r=FLOOR(RAND() * 401) + 100, then SELECT @r.
– Qian Chen
Mar 23 '16 at 6:55
3
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What is the difference between String.slice and String.substring?
...gt; stop, slice() will return the empty string. ("")
If start is negative: sets char from the end of string, exactly like substr() in Firefox. This behavior is observed in both Firefox and IE.
If stop is negative: sets stop to: string.length – Math.abs(stop) (original value), except bounded at 0 (...
Oracle取前N条记录方法 Oracle实现SELECT TOP N的方法 - 爬虫/数据库 - 清...
select * from ( select * from tablexxx order by xxx desc ) where rownum <= N
oracle数据库不支持mysql中limit, top功能,但可以通过rownum来限制返回的结果集的行数,rownum并不是用户添加的字段,而是oracle系统自动添加的。
In Unix, how do you remove everything in the current directory and below it?
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Practice safe computing. Simply go up one level in the hierarchy and don't use a wildcard expression:
cd ..; rm -rf -- <dir-to-remove>
The two dashes -- tell rm that <dir-to-remove> is not a command-line option, even whe...
Why is “origin/HEAD” shown when running “git branch -r”?
...igin/HEAD will point at that.
On GitHub, You can change this in the Admin settings for your GitHub repo. You can also do it from the command-line via
git remote set-head origin trunk
or delete it altogether via
git remote set-head origin -d
Example. Look at the 'Switch Branches' drop-down. tr...
Initializing a member array in constructor initializer
... editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
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How to discard all changes made to a branch?
... ) and I've made a number of changes, but I need to discard them all and reset it to match the repository version. I thought git checkout design would do it, but it just tells me I'm already in branch design and that I have 3 modified files.
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What's the purpose of the LEA instruction?
...tain computations, but that's not its primary purpose. The x86 instruction set was designed to support high-level languages like Pascal and C, where arrays—especially arrays of ints or small structs—are common. Consider, for example, a struct representing (x, y) coordinates:
struct Point
{
...
iOS White to Transparent Gradient Layer is Gray
...ll detail view that pops up at the bottom of the app. As you can see, I've set the colors from white to clear, but there's this strange gray tint that is showing up. Any ideas?
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Slicing of a NumPy 2d array, or how do I extract an mxm submatrix from an nxn array (n>m)?
I want to slice a NumPy nxn array. I want to extract an arbitrary selection of m rows and columns of that array (i.e. without any pattern in the numbers of rows/columns), making it a new, mxm array. For this example let us say the array is 4x4 and I want to extract a 2x2 array from it.
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