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How to add column if not exists on PostgreSQL?
...hich have no IF NOT EXISTS syntax - for example ALTER TABLE ... ADD CONSTRAINT.
– Tomasz Gandor
Apr 16 '19 at 9:51
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Sorting a Python list by two fields
...For example, the columns to be used as keys are all strings that cannot be converted to numbers. Secondly, one wants to sort in ascending order by one column and descending order by another column.
– coder.in.me
Sep 25 '16 at 9:00
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C# How can I check if a URL exists/is valid?
...e.g. images, files etc) HEAD usually works as advertised since it is baked into the server. Many programmers do not explicitly HEAD requests since the focus is normally on POST and GET. YMMV
– David Taylor
May 29 '09 at 15:53
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Copy table without copying data
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How could you convert show create table bar into a dynamically executable statement?
– Pacerier
Feb 2 '15 at 12:23
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How to resume Fragment from BackStack if exists
...ment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
}
}
EDIT
The problem is - when i launch A and then B, then press back button, B
is removed and ...
Primary key or Unique index?
...index on a column is an index on that column that also enforces the constraint that you cannot have two equal values in that column in two different rows. Example:
CREATE TABLE table1 (foo int, bar int);
CREATE UNIQUE INDEX ux_table1_foo ON table1(foo); -- Create unique index on foo.
INSERT INTO...
Terminating a script in PowerShell
... via CLI e.g. powershell -command "& module-function ...". I needed to convert those functions to throw to a wrapping try-catch and exit from that wrapping catch in order to actually output an error exit code.
– Josh
Mar 16 '16 at 14:37
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Performance of Java matrix math libraries? [closed]
...thing whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question:
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LaTeX: Prevent line break in a span of text
...at the point of the command. With the
optional argument, number, you can convert the \nolinebreak command
from a demand to a request. The number must be a number from 0 to 4.
The higher the number, the more insistent the request is.
Source: http://www.personal.ceu.hu/tex/breaking.htm#nolineb...
SQL WHERE.. IN clause multiple columns
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While this would work, it converts the uncorrelated query in the question into a correlated query. Unless the query optimizer is clever, this might give you O(n^2) performance :-(. But maybe I'm underestimating the optimizer...
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