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django models selecting single field
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thanks for the answer, what if I want to select only 1 or more fields (not all)?
– zentenk
Sep 21 '11 at 16:42
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How to check if mysql database exists
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SELECT SCHEMA_NAME
FROM INFORMATION_SCHEMA.SCHEMATA
WHERE SCHEMA_NAME = 'DBName'
If you just need to know if a db exists so you won't get an error when you try to create it, simply use (From here):
CREATE DATABASE IF NO...
What's the reason for “Error:Cannot determine Java VM executable in selected JDK”?
...ettings from project context menu (or default hit F4), then from left tab select Project and point correct Project SDK on dropdown.
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powershell - extract file name and extension
...tated, use the BaseName and Extension properties:
PS C:\> dir *.xlsx | select BaseName,Extension
BaseName Extension
-------- ---------
StackOverflow.com Test Config .xlsx
If you are given the file name as part of string...
Compare two files in Visual Studio
... the desktop. That's all!
Usage:
Open the Windows explorer via Win + E
Select two files to compare in the explorer
Drag and drop them as shown in the animation below:
After a few seconds (depending on the launch time of Visual Studio), the results will be shown in Visual Studio:
Note: It d...
Linq: GroupBy, Sum and Count
...a" is coming from, but the problem in the console app is that you're using SelectMany to look at each item in each group.
I think you just want:
List<ResultLine> result = Lines
.GroupBy(l => l.ProductCode)
.Select(cl => new ResultLine
{
ProductName =...
Modifying a subset of rows in a pandas dataframe
...The df.A==0 expression creates a boolean series that indexes the rows, 'B' selects the column. You can also use this to transform a subset of a column, e.g.:
df.loc[df.A==0, 'B'] = df.loc[df.A==0, 'B'] / 2
I don't know enough about pandas internals to know exactly why that works, but the basic is...
Linq to Sql: Multiple left outer joins
... .Where(s => s.Id == order.StatusId)
.DefaultIfEmpty()
select new { Order = order, Vendor = vendor, Status = status }
//Vendor and Status properties will be null if the left join is null
Here is another left join example
var results =
from expense in expenseDataConte...
Error 1046 No database Selected, how to resolve?
...ation.
If you're trying to do this via MySQL Workbench...
...you need to select the appropriate database/catalog in the drop down menu found above the :Object Browser: tab. You can specify the default schema/database/catalog for the connection - click the "Manage Connections" options under the SQL...
How to create P12 certificate for iOS distribution
...hain Access where it will be matched up with the private key. You can then select the cert, and open the arrow to also select the private key and export them together as a .p12 file from Keychain Access.
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