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Count number of records returned by group by
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You can do both in one query using the OVER clause on another COUNT
select
count(*) RecordsPerGroup,
COUNT(*) OVER () AS TotalRecords
from temptable
group by column_1, column_2, column_3, column_4
share
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Converting RGB to grayscale/intensity
...th 32 bits i.e. 4 bytes per pixel
unsigned int fourBytes;
unsigned char r,g,b;
for (int index=0;index<width*height;index++)
{
fourBytes=pntrBWImage[index];//caches 4 bytes at a time
r=(fourBytes>>16);
g=(fourBytes>>8);
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Split function equivalent in T-SQL?
...AR(2048) = 'Mike/John/Miko/Matt'; DECLARE CaracString NVARCHAR(1) = '/'; SELECT * FROM dbo.FnSplitString (VarString, CaracString)
– fernando yevenes
Feb 8 '19 at 15:57
ad...
SQL join: selecting the last records in a one-to-many relationship
... want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes?
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JComboBox Selection Change Listener?
...istener() will work, too. You may get 2 ItemEvents, though, one for the deselection of the previously selected item, and another for the selection of the new item. Just don't use both event types!
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How do I cast a string to integer and have 0 in case of error in the cast with PostgreSQL?
...dn't want the overhead of a function. I came up with the following query:
SELECT myfield::integer FROM mytable WHERE myfield ~ E'^\\d+$';
Postgres shortcuts its conditionals, so you shouldn't get any non-integers hitting your ::integer cast. It also handles NULL values (they won't match the regex...
Selecting element by data attribute
Is there an easy and straight-forward method to select elements based on their data attribute? For example, select all anchors that has data attribute named customerID which has value of 22 .
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What is the difference between std::array and std::vector? When do you use one over other? [duplicat
...inter to an array; e.g., C library routines. (As an aside, std::vector<char> buf(8192); is a great way to allocate a local buffer for calls to read/write or similar without directly invoking new.)
That said, the lack of that extra level of indirection, plus the compile-time constant size, ca...
PHP passing $_GET in linux command prompt
...RL in single quotes, as the ? and & in the query portion are shell metacharacters (single char wildcard + "run this command in the background").
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Why are Where and Select outperforming just Select?
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Select iterates once over the entire set and, for each item, performs a conditional branch (checking for validity) and a + operation.
Where+Select creates an iterator that skips invalid elements (doesn't yield them), perform...