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Computed / calculated / virtual / derived columns in PostgreSQL
...e to list it explicitly.
Can also be supported with a matching expression index - provided the function is IMMUTABLE. Like:
CREATE FUNCTION col(tbl) ... AS ... -- your computed expression here
CREATE INDEX ON tbl(col(tbl));
Alternatives
Alternatively, you can implement similar functionality wi...
Extract elements of list at odd positions
...efault (0) would be used. So the first element (at position 0, because the indexes are 0-based) would be selected. In this case the second element will be selected.
Because the second element is omitted, the default is being used (the end of the list). So the list is being iterated from the second ...
Get real path from URI, Android KitKat new storage access framework [duplicate]
... column, sel, new String[]{ id }, null);
String filePath = "";
int columnIndex = cursor.getColumnIndex(column[0]);
if (cursor.moveToFirst()) {
filePath = cursor.getString(columnIndex);
}
cursor.close();
Reference: I'm not able to find the post that this solution is taken from. I wanted ...
PHP学习必看的一些书 - IT书籍推荐 - 清泛网 - 专注C/C++及内核技术
PHP学习必看的一些书对应初学的PHP，应该买什么样的书？到处问人，到处求助？ 该文章列举了一些书籍，感觉还行，特此重新整理了一下。觉得有些言过其实了，或...对应初学的PHP，应该买什么样的书？到处问人，到处求助？ ...
PHP 安装 ZIP 扩展 - 更多技术 - 清泛网 - 专注C/C++及内核技术
PHP 安装 ZIP 扩展php_zip_extension一、安装libzipcd usr local srcwget https: libzip org download libzip-1 3 2 tar gztar zxf libzip-1 3 2 tar gzcd libzip-1 3 2 configuremake && make install如 一、安装libzip
cd /usr/local/src
wget https://libzip.org/download/libzip-1.3.2.tar.gz
...
Cast to int vs floor
...its being dropped”. See (although it is written for C): blog.frama-c.com/index.php?post/2013/10/09/…
– Pascal Cuoq
Dec 30 '14 at 22:23
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Determine project root from a running node.js application
...tach to this object will be available everywhere in your app. So, in your index.js (or app.js or whatever your main app file is named), you can just define a global variable:
// index.js
var path = require('path');
global.appRoot = path.resolve(__dirname);
// lib/moduleA/component1.js
require(app...
Making heatmap from pandas DataFrame
...numpy as np
from pandas import DataFrame
import matplotlib.pyplot as plt
index = ['aaa', 'bbb', 'ccc', 'ddd', 'eee']
columns = ['A', 'B', 'C', 'D']
df = DataFrame(abs(np.random.randn(5, 4)), index=index, columns=columns)
plt.pcolor(df)
plt.yticks(np.arange(0.5, len(df.index), 1), df.index)
plt.xt...
How do I check if a column is empty or null in MySQL?
...unction on a column in the WHERE clause as it makes it difficult to use an index. If you simply want to check if a column is null or empty, you may be better off doing this:
SELECT myCol
FROM MyTable
WHERE MyCol IS NULL OR MyCol = ''
See TRIM COALESCE and IS NULL for more info.
Also Working with ...
Configure WAMP server to send email
...th me.
If you just want to test, here is a great tool for testing mail locally, that requires almost no configuration:
http://www.toolheap.com/test-mail-server-tool/
It worked right off the bat for me, hope this helps you.
...