大约有 43,000 项符合查询结果（耗时：0.0268秒） [XML]
Entity Framework: There is already an open DataReader associated with this Command
...y loading (IQueriable).
foreach (var user in _dbContext.Users)
{
}
Converting the IQueriable collection into other enumerable collection will solve this problem.
example
_dbContext.Users.ToList()
Note: .ToList() creates a new set every-time and it can cause the performance issue if you a...
Select mySQL based only on month and year
... It is index friendly, but strtotime gives you int and you need to convert it to date for mysql first.
– piotrm
Feb 1 '12 at 23:26
...
Received an invalid column length from the bcp client for colid 6
...h match = Regex.Match(ex.Message.ToString(), pattern);
var index = Convert.ToInt32(match.Value) -1;
FieldInfo fi = typeof(SqlBulkCopy).GetField("_sortedColumnMappings", BindingFlags.NonPublic | BindingFlags.Instance);
var sortedColumns = fi.GetValue(bulkCopy);
var it...
How does the bitwise complement operator (~ tilde) work?
...numbers are stored in 2's complement form,
the acquired result we have to convert into 2's complement( first perform 1's complement and just add 1 to 1's complement).
all the one will become zeros,except most significant bit 1(which is our sign representation of the number,that means for remaining...
Converting many 'if else' statements to a cleaner approach [duplicate]
...
You could have a Converter interface. Then you could create a class for each Mimetype like:
public interface Converter {
public void convertToMp3();
public void convertToOgg();
}
public class MpegConverter implements Converter {
...
Is there a way to chain multiple value converters in XAML?
...y Silverlight project.
Here's my implementation of it:
public class ValueConverterGroup : List<IValueConverter>, IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
...
Equals(=) vs. LIKE
...archar2. If you compare char with char. Before compare the database first convert the length of first 'variable' to the same of second. If you compare char and varchar2 the database will do nothing. docs.oracle.com/cd/A64702_01/doc/server.805/a58236/c_char.htm
– xild
...
Sort a Map by values
...
Java 8 offers a new answer: convert the entries into a stream, and use the comparator combinators from Map.Entry:
Stream<Map.Entry<K,V>> sorted =
map.entrySet().stream()
.sorted(Map.Entry.comparingByValue());
This will let you ...
Python class inherits object
...I am not 101% sure about this point (wether all builtin types were already converted to new-style classes when new-style classes were introduced) - I might just be plain wrong, or this might only have concerned some of the standard lib's (but not builtin) types. But yet I think it should be better t...
Remove duplicate rows in MySQL
...n the backup_employee table
⇒ Using this approach, 1.6M registers were converted into 6k in less than 200s.
Chetan, following this process, you could fast and easily remove all your duplicates and create a UNIQUE constraint by running:
CREATE TABLE tmp_jobs LIKE jobs;
ALTER TABLE tmp_jobs ADD...