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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...
How do I clear all options in a dropdown box?
...
You can use the following to clear all the elements.
var select = document.getElementById("DropList");
var length = select.options.length;
for (i = length-1; i >= 0; i--) {
select.options[i] = null;
}
...
How do I get SUM function in MySQL to return '0' if no values are found?
...
Use COALESCE to avoid that outcome.
SELECT COALESCE(SUM(column),0)
FROM table
WHERE ...
To see it in action, please see this sql fiddle: http://www.sqlfiddle.com/#!2/d1542/3/0
More Information:
Given three tables (one with all numbers, one with all nul...
How to make connection to Postgres via Node.js
...values($1, $2)", ['John', x]);
x = x - 1;
}
var query = client.query("SELECT * FROM junk");
//fired after last row is emitted
query.on('row', function(row) {
console.log(row);
});
query.on('end', function() {
client.end();
});
//queries can be executed either via text/parameter val...
How to export table as CSV with headings on Postgresql?
...
@arilwan psql -c "\COPY (SELECT * FROM mytable) TO STDOUT" > mytable.csv
– Juha Palomäki
Jun 6 '19 at 16:00
...
Visual Studio hot keys change occasionally, specifically F6 vs Ctrl-Shift-B for building. WHY?
...
This is because you might have selected "General Development Settings" as your default environment settings for your Visual Studio (which usually we do on the first launch of VS after installing it as it pops up a dialogue box to choose default environment...
Selecting an element in iFrame jQuery
...rame. All the elements in that loaded page have their tokenid-s. I need to select the elements by those tokenid-s. Means - I click on an element on the main page and select corresponding element in the page in the iFrame. With the help of jQuery I'm doing it in the following way:
...
PostgreSQL: insert from another table
...
Just supply literal values in the SELECT:
INSERT INTO TABLE1 (id, col_1, col_2, col_3)
SELECT id, 'data1', 'data2', 'data3'
FROM TABLE2
WHERE col_a = 'something';
A select list can contain any value expression:
But the expressions in the select list do...
How to open a specific port such as 9090 in Google Compute Engine
...hoose "Firewalls rules"
Choose "Create Firewall Rule"
To apply the rule to select VM instances, select Targets > "Specified target tags", and enter into "Target tags" the name of the tag. This tag will be used to apply the new firewall rule onto whichever instance you'd like. Then, make sure the ...
Select elements by attribute
...
Do you mean can you select them? If so, then yes:
$(":checkbox[myattr]")
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