大约有 43,000 项符合查询结果（耗时：0.0475秒） [XML]
Random record from MongoDB
...llection.
db.mycoll.aggregate([{ $sample: { size: 1 } }])
If you want to select the random document(s) from a filtered subset of the collection, prepend a $match stage to the pipeline:
// Get one random document matching {a: 10} from the mycoll collection.
db.mycoll.aggregate([
{ $match: { a:...
How to change collation of database, table, column?
...he OP asked:
How to change collation of database, table, column?
The selected answer just states it on table level.
Changing it database wide:
ALTER DATABASE <database_name> CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Changing it per table:
ALTER TABLE <table_name> CON...
How does a “stack overflow” occur and how do you prevent it?
...w (in C/C++, at least) is to declare some enormous variable on the stack.
char hugeArray[100000000];
That'll do it.
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How to COUNT rows within EntityFramework without loading contents?
... where o.ID == '1'
from t in o.MyTable
select t).Count();
Method syntax:
var count = context.MyContainer
.Where(o => o.ID == '1')
.SelectMany(o => o.MyTable)
.Count()
Both generate the same SQL query.
...
Vim indent xml file
... that you don't have to alter your vimrc file. Plus it is easier to format select portions of the XML file (something I happen to do a lot).
First, highlight the XML you want to format.
Then, in normal mode, type ! xmllint --format -
Your command-line at the bottom will look like this:
:'<,'&...
How do you return the column names of a table?
...
Not sure if there is an easier way in 2008 version.
USE [Database Name]
SELECT COLUMN_NAME,*
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName' AND TABLE_SCHEMA='YourSchemaName'
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Fastest way to count exact number of rows in a very large table?
I have come across articles that state that SELECT COUNT(*) FROM TABLE_NAME will be slow when the table has lots of rows and lots of columns.
...
Open two instances of a file in a single Visual Studio session
...
Here's how to do it...
Select the tab you want two copies of
Select menu Window → New Window from the menu.
Right click the new tab and select New Vertical Tab Group
If New Window is not listed in the *Window menu note that the command does exi...
oracle group 取每组第一条 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...type字段分组,code排序,取出每组中的第一条记录方法一：select type,min(code) from group_infogro...Oracle查询：取出每组中的第一条记录
按type字段分组，code排序，取出每组中的第一条记录：
方法一：
select type,min(code) from group_info grou...
Renaming projects in Xcode 4
...matically change all project-name-related entries and will allow you to de-select some of them if you want.
Nice.
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