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The cast to value type 'Int32' failed because the materialized value is null
...
where u.ID == userID
select (int?)ch.Amount).Sum() ?? 0;
This first casts to int? to tell the C# compiler that this expression can indeed return null, even though Sum() returns an int. Then we use the normal ?? operator to handle the null case....
Eclipse: Enable autocomplete / content assist
...efault in Eclipse you only have to press Ctrl-space for autocomplete. Then select the desired method and wait 500ms for the javadoc info to pop up.
If this doesn't work go to the Eclipse Windows menu -> Preferences -> Java -> Editor -> Content assist and check your settings here
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Values of disabled inputs will not be submitted
...lements support the disabled attribute: BUTTON, INPUT,
OPTGROUP, OPTION, SELECT, and TEXTAREA.
This attribute is inherited but local declarations override the
inherited value.
How disabled elements are rendered depends on the user agent. For
example, some user agents "gray out" disab...
How to set -source 1.7 in Android Studio and Gradle
...to run on 1.7 (or 1.6 if you prefer). Click File --> Project Structure. Select the module you want to run and then under "Source Compatibility" and "Target Compatibility", select 1.7. Click "OK".
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Hidden Features of MySQL
...that has an integer type,
you can also refer to the column as "_rowid" in SELECT statements.
In MySQL, the name of a PRIMARY KEY is PRIMARY
Currently, only InnoDB (v5.1?) tables support foreign keys.
Usually, you create all the indexes you need when you are creating tables.
Any column declared...
How to export DataTable to Excel
...tring[] columnNames = dataTable.Columns
.Cast<DataColumn>()
.Select(column => column.ColumnName)
.ToArray();
var header = string.Join(",", columnNames.Select(name => $"\"{name}\""));
lines.Add(header);
var valueLines = dataTable.AsEnumerable()
.Select(row => string.J...
How do I URl encode something in Node.js?
...
You can use JavaScript's encodeURIComponent:
encodeURIComponent('select * from table where i()')
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Best way to do nested case statement logic in SQL Server
...
You could try some sort of COALESCE trick, eg:
SELECT COALESCE(
CASE WHEN condition1 THEN calculation1 ELSE NULL END,
CASE WHEN condition2 THEN calculation2 ELSE NULL END,
etc...
)
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Comparison of full text search engine - Lucene, Sphinx, Postgresql, MySQL?
... up the firstname field as shown.
http://localhost:8983/solr/collection1/select?q=firstname:john^2&lastname:john
As you can see, firstname field is boosted up with a score of 2.
More on SolrRelevancy
searching and indexing speed
The speed is unbelievably fast and no compromise o...
How to get the raw value an field?
...
Spudly has a useful answer that he deleted:
Just use the CSS :invalid selector for this.
input[type=number]:invalid {
background-color: #FFCCCC;
}
This will trigger your element to turn red whenever a non-numeric
valid is entered.
Browser support for <input type='number'>...