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How to concatenate columns in a Postgres SELECT?
...ring concatenation operator (||) accepts non-string
input, so long as at least one input is of a string type, as shown in
Table 9.8. For other cases, insert an explicit coercion to text [...]
Bold emphasis mine. The 2nd example (select a||', '||b from foo) works for any data types since the u...
How to drop a table if it exists?
... 'dbo')
drop table dbo.Scores;
Most modern RDBMS servers provide, at least, basic INFORMATION_SCHEMA support, including: MySQL, Postgres, Oracle, IBM DB2, and Microsoft SQL Server 7.0 (and greater).
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Add a column to a table, if it does not already exist
...r to only perform the minimum reads necessary to evaluate the EXISTS... at least in SQL Server. Other DB engines may have a more or less efficient query optimizer.
– Kenneth Cochran
Jul 21 '15 at 16:56
...
When to use symbols instead of strings in Ruby?
If there are at least two instances of the same string in my script, should I instead use a symbol?
4 Answers
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Are unused CSS images downloaded?
...
No, they are not downloaded, not at least in Firefox, IE8 and Chrome.
An easy way to test this:
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
.nonexistent {
background: url('index.php?foo');
...
Node.js Mongoose.js string to ObjectId function
...xpects the property to be of type ObjectId, the conversion is implicit, at least this seems to be the case in 4.7.8.
You could use something like this however, which gives a bit more flex:
function toObjectId(ids) {
if (ids.constructor === Array) {
return ids.map(mongoose.Types.Object...
How do I provide a username and password when running “git clone git@remote.git”?
...counts at a place like GitHub or Heroku, you'll have multiple ssh keys (at least one per account). To pick which account you want to log in as, you have to tell ssh which private key to use.
For example, suppose you had two GitHub accounts: foo and bar. Your ssh key for foo is ~/.ssh/foo_github_...
in_array multiple values
... values to say that $haystack is a superset of $target.
To verify that at least one value in $target is also in $haystack, you can do this check:
if(count(array_intersect($haystack, $target)) > 0){
// at least one of $target is in $haystack
}
...
Center a button in a Linear layout
...
At least for me android:gravity="center" LinearLayout attribute did the trick. Thank you bro!
– tthreetorch
Apr 27 '19 at 17:16
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Overriding id on create in ActiveRecord
...ey remained unchanged. Other answers only worked sometimes.
For MySQL at least, assigning an id below the auto increment id number does not work unless you use update_column. For example,
p = Post.create(:title => 'Test')
p.id
=> 20 # 20 was the id the auto increment gave it
p2 = Post.cre...