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quick random row selection in Postgres
... need to first do a SELECT COUNT(*) to figure out the value of N.
Update (by Antony Hatchkins)
You must use floor here:
SELECT myid FROM mytable OFFSET floor(random()*N) LIMIT 1;
Consider a table of 2 rows; random()*N generates 0 <= x < 2 and for example SELECT myid FROM mytable OFFSET 1....
Select the values of one property on all objects of an array in PowerShell
...eInfo objects. You can always inspect the type coming through the pipeline by piping to Get-Member (alias gm).
ls | select -Property Name | gm
So, to expand the object to be that of the type of property you're looking at, you can do the following:
ls | select -ExpandProperty Name
In your case,...
Error :Request header field Content-Type is not allowed by Access-Control-Allow-Headers
...
As hinted at by this post Error in chrome: Content-Type is not allowed by Access-Control-Allow-Headers just add the additional header to your web.config like so...
<httpProtocol>
<customHeaders>
<add name="Access-...
Count work days between two dates
...ore robust but also more obscure solution is to replace the last two lines by: -(case datepart(dw, @StartDate)+@@datefirst when 8 then 1 else 0 end) -(case datepart(dw, @EndDate)+@@datefirst when 7 then 1 when 14 then 1 else 0 end)
– Torben Klein
Aug 20 '12 at ...
Difference between return and exit in Bash functions
...;
Causes a function to stop executing and return the value specified by n to its caller. If n is omitted, the return status is that of the last command executed in the function body.
... on exit [n]:
Cause the shell to exit with a status of n. If n is omitted, the exit status is ...
Debugging “Element is not clickable at point” error
...
This is caused by following 3 types:
1.The element is not visible to click.
Use Actions or JavascriptExecutor for making it to click.
By Actions:
WebElement element = driver.findElement(By("element_path"));
Actions actions = new Action...
Finding duplicate values in MySQL
...
Do a SELECT with a GROUP BY clause. Let's say name is the column you want to find duplicates in:
SELECT name, COUNT(*) c FROM table GROUP BY name HAVING c > 1;
This will return a result with the name value in the first column, and a count of ho...
Dealing with commas in a CSV file
...ggestions on how to handle a csv file that is being created, then uploaded by our customers, and that may have a comma in a value, like a company name.
...
C pointers : pointing to an array of fixed size
...time constant), the only proper way to pass such an array to a function is by using a pointer-to-array parameter
void foo(char (*p)[10]);
(in C++ language this is also done with references
void foo(char (&p)[10]);
).
This will enable language-level type checking, which will make sure that...
When to use in vs ref vs out
...efer to the 'comments (Community Additions)' section in the link mentioned by you. It is an error which is corrected in VS 2008 documentation.
– Bharat Ram V
Aug 12 '13 at 8:07
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