大约有 40,000 项符合查询结果（耗时：0.0427秒） [XML]
How to 'insert if not exists' in MySQL?
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Solution:
INSERT INTO `table` (`value1`, `value2`)
SELECT 'stuff for value1', 'stuff for value2' FROM DUAL
WHERE NOT EXISTS (SELECT * FROM `table`
WHERE `value1`='stuff for value1' AND `value2`='stuff for value2' LIMIT 1)
Explanation:
The innermost query
SELECT *...
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...
How can I query a value in SQL Server XML column
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select
Roles
from
MyTable
where
Roles.value('(/root/role)[1]', 'varchar(max)') like 'StringToSearchFor'
These pages will show you more about how to query XML in T-SQL:
Querying XML fields using t-sql
Flattening XML Dat...
Saving results with headers in Sql Server Management Studio
...reopen SSMS after changing this option.
On the SQL Editor Toolbar you can select save to file without having to restart SSMS
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Finding # occurrences of a character in a string in Ruby
... Ruby method (1.9...) that can help me find the number of occurrences of a character in a string. I'm looking for all occurrences, not just the first one.
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Create code first, many to many, with additional fields in association table
...OfMembers = context.Members
.Where(m => m.LastName == "Smith")
.SelectMany(m => m.MemberComments.Select(mc => mc.Comment))
.ToList();
... or ...
var commentsOfMembers = context.MemberComments
.Where(mc => mc.Member.LastName == "Smith")
.Select(mc => mc.Comment)
...
Get first day of week in SQL Server
...in that there should be some sensible logic built in to round up or down:
SELECT DATEDIFF(YEAR, '2010-01-01', '2011-12-31');
SELECT DATEDIFF(YEAR, '2010-12-31', '2011-01-01');
To answer how to get a Sunday:
If you want a Sunday, then pick a base date that's not a Monday but rather a Sunday. For ...
How to get a number of random elements from an array?
...- Math.random());
// Get sub-array of first n elements after shuffled
let selected = shuffled.slice(0, n);
DEMO:
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How do you count the lines of code in a Visual Studio solution?
...solution's directory:
PS C:\Path> (gci -include *.cs,*.xaml -recurse | select-string .).Count
8396
PS C:\Path>
That will count the non-blank lines in all the solution's .cs and .xaml files. For a larger project, I just used a different extension list:
PS C:\Other> (gci -include *.cs,*....
Escape double quote character in XML
Is there an escape character for a double quote in xml? I want to write a tag like:
8 Answers
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