大约有 40,000 项符合查询结果（耗时：0.0217秒） [XML]
Accessing inactive union member and undefined behavior?
I was under the impression that accessing a union member other than the last one set is UB, but I can't seem to find a solid reference (other than answers claiming it's UB but without any support from the standard).
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What makes a SQL statement sargable?
...non-sargable is to include a field inside a function in the where clause:
SELECT ... FROM ...
WHERE Year(myDate) = 2008
The SQL optimizer can't use an index on myDate, even if one exists. It will literally have to evaluate this function for every row of the table. Much better to use:
WHERE myDat...
SQL Server query to find all permissions/access for all users in a database
...s the user/role has on an object. Examples could include CONNECT, EXECUTE, SELECT
DELETE, INSERT, ALTER, CONTROL, TAKE OWNERSHIP, VIEW DEFINITION, etc.
This value may not be populated for all roles. Some built in roles have implicit permission
d...
XPath OR operator for different nodes
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If you want to select only one of two nodes with union operator, you can use this solution:
(//bookstore/book/title | //bookstore/city/zipcode/title)[1]
share
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How do I change db schema to dbo
...which will generate a set of ALTER sCHEMA statements for all your talbes:
SELECT 'ALTER SCHEMA dbo TRANSFER ' + TABLE_SCHEMA + '.' + TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'jonathan'
You then have to copy and run the statements in query analyzer.
Here's an older script t...
Split function equivalent in T-SQL?
...AR(2048) = 'Mike/John/Miko/Matt'; DECLARE CaracString NVARCHAR(1) = '/'; SELECT * FROM dbo.FnSplitString (VarString, CaracString)
– fernando yevenes
Feb 8 '19 at 15:57
ad...
What is the most efficient/elegant way to parse a flat table into a tree?
...port recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELECT m.* FROM MyTABLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive queries in MySQL 8.0 in my presentation Recursive ...
CSS “and” and “or”
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&& works by stringing-together multiple selectors like-so:
<div class="class1 class2"></div>
div.class1.class2
{
/* foo */
}
Another example:
<input type="radio" class="class1" />
input[type="radio"].class1
{
/* foo */
}
|| works by se...
UIButton: set image for selected-highlighted state
I set an images for button's states Normal,Highlighted and Selected, but when the button in selected state and I press/highlight it I didn't see my highlighted image but just grayed picture.
Is it possible to set an image for highlighted state when the button selected?
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Build an ASCII chart of the most commonly used words in a given text [closed]
...bars only the last line break is required.
DECLARE @ VARCHAR(MAX),@F REAL SELECT @=BulkColumn FROM OPENROWSET(BULK'A',
SINGLE_BLOB)x;WITH N AS(SELECT 1 i,LEFT(@,1)L UNION ALL SELECT i+1,SUBSTRING
(@,i+1,1)FROM N WHERE i<LEN(@))SELECT i,L,i-RANK()OVER(ORDER BY i)R INTO #D
FROM N WHERE L LIKE'[A-Z...