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Select rows of a matrix that meet a condition
...20, ncol = 4)
colnames(m) <- letters[1:4]
The following command will select the first row of the matrix above.
subset(m, m[,4] == 16)
And this will select the last three.
subset(m, m[,4] > 17)
The result will be a matrix in both cases.
If you want to use column names to select columns...
T-SQL datetime rounded to nearest minute and nearest hours with using functions
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declare @dt datetime
set @dt = '09-22-2007 15:07:38.850'
select dateadd(mi, datediff(mi, 0, @dt), 0)
select dateadd(hour, datediff(hour, 0, @dt), 0)
will return
2007-09-22 15:07:00.000
2007-09-22 15:00:00.000
The above just truncates the seconds and minutes, producing the resu...
Why use the INCLUDE clause when creating an index?
...ot in the WHERE/JOIN/GROUP BY/ORDER BY, but only in the column list in the SELECT clause.
The INCLUDE clause adds the data at the lowest/leaf level, rather than in the index tree.
This makes the index smaller because it's not part of the tree
INCLUDE columns are not key columns in the index, so th...
How to change Xcode Project name
...
For Xcode 4 or later:
Open a project
Select Project Navigator
Highlight project name
Single click on project name
For Xcode 3:
Open a project > Menu > Project > Rename ...
...
Getting attribute using XPath
...e), for
the first element?
Use:
/*/book[1]/title/@lang
This means:
Select the lang attribute of the title element that is a child of the first book child of the top element of the XML document.
To get just the string value of this attribute use the standard XPath function string():
string(...
Psql list all tables
...This is where the INFORMATION_SCHEMA comes to the rescue. To list tables:
SELECT table_name FROM information_schema.tables WHERE table_schema = 'public';
BTW, if you ever want to see what psql is doing in response to a backslash command, run psql with the -E flag. eg:
$ psql -E regress
regre...
Postgres: Distinct but only for one column
...h names (having more than 1 mio. rows), but I have also many duplicates. I select 3 fields: id , name , metadata .
3 Ans...
How do I select the parent form based on which submit button is clicked?
...
You can select the form like this:
$("#submit").click(function(){
var form = $(this).parents('form:first');
...
});
However, it is generally better to attach the event to the submit event of the form itself, as it will tri...
SQL Server - copy stored procedures from one db to another
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Right click on database
Tasks
Generate Scripts
Select the objects you wish to script
Script to File
Run generated scripts against target database
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What is the benefit of zerofill in MySQL?
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When you select a column with type ZEROFILL it pads the displayed value of the field with zeros up to the display width specified in the column definition. Values longer than the display width are not truncated. Note that usage of ZER...