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How to check for an undefined or null variable in JavaScript?
...s the truthiness. Which FYI is also equivalent to if (var) which will be cast to boolean, so basically completely useless...
– Cyril CHAPON
Jun 26 '18 at 9:42
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How to request a random row in SQL?
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See this post: SQL to Select a random row from a database table. It goes through methods for doing this in MySQL, PostgreSQL, Microsoft SQL Server, IBM DB2 and Oracle (the following is copied from that link):
Select a random row with MySQL:
SELE...
Generating random integer from a range
... properly uniform distributed solution is
output = min + (rand() % static_cast<int>(max - min + 1))
Except when the size of the range is a power of 2, this method produces biased non-uniform distributed numbers regardless the quality of rand(). For a comprehensive test of the quality of thi...
C++ Tuple vs Struct
...ayout is implementation defined so not compatible (and thus you should not cast between either representation) and in general I would expect no difference performance-wise (at least in Release) thanks to the inlining of get<N>.
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Table name as variable
...mpare data between the same tables of different databases:
static query:
SELECT * FROM [DB_ONE].[dbo].[ACTY]
EXCEPT
SELECT * FROM [DB_TWO].[dbo].[ACTY]
since I want easily change tha name of table and schema I have created this dynamic query:
declare @schema varchar(50)
declare @table varchar(5...
SQL Server Profiler - How to filter trace to only display events from one database?
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Under Trace properties > Events Selection tab > select show all columns. Now under column filters, you should see the database name. Enter the database name for the Like section and you should see traces only for that database.
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MFC CListCtrl使用方法详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...DWORD dwStyle = m_list.GetExtendedStyle();
dwStyle |= LVS_EX_FULLROWSELECT;//选中某行使整行高亮（只适用与report风格的listctrl）
dwStyle |= LVS_EX_GRIDLINES;//网格线（只适用与report风格的listctrl）
dwStyle |= LVS_EX_CHECKBOXES;//item前生成checkbox...
jQuery - select all text from a textarea
...can I make it so when you click inside a textarea, its entire content gets selected?
6 Answers
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Swapping column values in MySQL
...rows affected (0.08 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM swaptest;
+------+------+
| X | Y |
+------+------+
| 1 | 2 |
| 3 | 4 |
| -5 | -8 |
| -13 | 27 |
+------+------+
4 rows in set (0.00 sec)
mysql>
Here is the swap being performed
m...
Preventing an image from being draggable or selectable without using JS
Does anyone know of a way to make an image not draggable and not selectable -- at the same time -- in Firefox, without resorting to Javascript? Seems trivial, but here's the issue:
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