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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
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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...
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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Center a button in a Linear layout
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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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Are unused CSS images downloaded?
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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');
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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...
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
}
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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...
Multi-gradient shapes
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I don't think you can do this in XML (at least not in Android), but I've found a good solution posted here that looks like it'd be a great help!
ShapeDrawable.ShaderFactory sf = new ShapeDrawable.ShaderFactory() {
@Override
public Shader resize(int width, i...