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Fastest way to count exact number of rows in a very large table?
...ECT COUNT(*) FROM TABLE_NAME will be slow when the table has lots of rows and lots of columns.
25 Answers
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C++常用排序算法汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...小到大
*/
void Select_Sort1(int *arr,int len)
{
int i,j;
for(i=0;i<len;i++)
for(j=i+1;j<len;j++)
if(arr[i] > arr[j])
{
int exchange = arr[i];
arr[i] = arr[j];
arr[j] = exchange;
}
}
/*
第二种形式的选择排序，减少了元素互换的操作
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Why can't static methods be abstract in Java?
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Because "abstract" means: "Implements no functionality", and "static" means: "There is functionality even if you don't have an object instance". And that's a logical contradiction.
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Purpose of Python's __repr__
... for someone confused over this, imho. (If I've gone to far, just re-edit, and I'll owe you a beer.)
– Roger Pate
Dec 31 '09 at 6:47
2
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How to generate a number of most distinctive colors in R?
I am plotting a categorical dataset and want to use distinctive colors to represent different categories. Given a number n , how can I get n number of MOST distinctive colors in R? Thanks.
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Postgresql - change the size of a varchar column to lower length
I have a question about the ALTER TABLE command on a really large table (almost 30 millions rows).
One of its columns is a varchar(255) and I would like to resize it to a varchar(40) .
Basically, I would like to change my column by running the following command:
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Attempt to set a non-property-list object as an NSUserDefaults
... only store things like NSArray, NSDictionary, NSString, NSData, NSNumber, and NSDate in NSUserDefaults.
You need to convert the object to NSData (like you have in some of the code) and store that NSData in NSUserDefaults. You can even store an NSArray of NSData if you need to.
When you read back ...
PDO closing connection
...ber of other reasons. When connecting or running a query, catch any error, and if it is "MySQL has gone away", attempt to connect again or run the query a second time.
– Frank Forte
Dec 14 '17 at 20:50
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What's the difference between SCSS and Sass?
...een reading, Sass is a language that makes CSS more powerful with variable and math support.
13 Answers
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How to combine paths in Java?
...path2 is an absolute path. The Java version will drop the leading / or \ and treat it as a relative path.
– finnw
Feb 12 '10 at 18:17
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