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Extracting specific columns in numpy array
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I assume you wanted columns 1 and 9?
To select multiple columns at once, use
X = data[:, [1, 9]]
To select one at a time, use
x, y = data[:, 1], data[:, 9]
With names:
data[:, ['Column Name1','Column Name2']]
You can get the names from data.dtype.names…
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Equivalent of *Nix 'which' command in PowerShell?
...or of giving you the path you'll need to pipe the output of get-command to select -expandproperty Path.
– Casey
Jul 29 '15 at 12:37
6
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Printing the value of a variable in SQL Developer
...utput).
Press the "+" button at the top of the Dbms Output window and then select an open database connection in the dialog that opens.
In SQL*Plus:
SET SERVEROUTPUT ON
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Is there any performance gain in indexing a boolean field?
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It depends on the actual queries and the selectivity of the index/query combination.
Case A: condition WHERE isok = 1 and nothing else there:
SELECT *
FROM tableX
WHERE isok = 1
If the index is selective enough (say you have 1M rows and only 1k have isok = 1), ...
Stored procedure slow when called from web, fast from Management Studio
...ariables.
eg. change:
ALTER PROCEDURE [dbo].[sproc]
@param1 int,
AS
SELECT * FROM Table WHERE ID = @param1
to:
ALTER PROCEDURE [dbo].[sproc]
@param1 int,
AS
DECLARE @param1a int
SET @param1a = @param1
SELECT * FROM Table WHERE ID = @param1a
Seems strange, but it fixed my problem.
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Why can't radio buttons be “readonly”?
...ton by disabling only the un-checked radio buttons. It keeps the user from selecting a different value, and the checked value will always post on submit.
Using jQuery to make readonly:
$(':radio:not(:checked)').attr('disabled', true);
This approach also worked for making a select list readonly, ...
LAST_INSERT_ID() MySQL
...RT INTO table2 (parentid,otherid,userid) VALUES (LAST_INSERT_ID(), 4, 1);
SELECT MAX(id) FROM table1;
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SQL Server - where is “sys.functions”?
... easy enough to roll your own:
CREATE VIEW my_sys_functions_equivalent
AS
SELECT *
FROM sys.objects
WHERE type IN ('FN', 'IF', 'TF') -- scalar, inline table-valued, table-valued
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How can I select an element by name with jQuery?
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You can use the jQuery attribute selector:
$('td[name ="tcol1"]') // matches exactly 'tcol1'
$('td[name^="tcol"]' ) // matches those that begin with 'tcol'
$('td[name$="tcol"]' ) // matches those that end with 'tcol'
$('td[name*="tcol"]' ) // matche...
Use '=' or LIKE to compare strings in SQL?
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To see the performance difference, try this:
SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name = B.name
SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name LIKE B.name
Comparing strings with '=' is muc...