大约有 46,000 项符合查询结果（耗时：0.0291秒） [XML]
SQL - find records from one table which don't exist in another
...shortest statement, and may be quickest if your phone book is very short:
SELECT *
FROM Call
WHERE phone_number NOT IN (SELECT phone_number FROM Phone_book)
alternatively (thanks to Alterlife)
SELECT *
FROM Call
WHERE NOT EXISTS
(SELECT *
FROM Phone_book
WHERE Phone_book.phon...
Get selected option text with JavaScript
...
Try options
function myNewFunction(sel) {
alert(sel.options[sel.selectedIndex].text);
}
<select id="box1" onChange="myNewFunction(this);">
<option value="98">dog</option>
<option value="7122">cat</option>
<option value="142">bird</option&g...
ASP.NET Identity reset password
...
Thank you for your answer. It works like a charm for me.
– Thomas.Benz
Mar 16 '17 at 13:43
4
...
How to drive C#, C++ or Java compiler to compute 1+2+3+…+1000 at compile time?
...
C# example to error at compile time.
class Foo
{
const char Sum = (1000 + 1) * 1000 / 2;
}
Produces the following compilation error:
Constant value '500500' cannot be converted to a 'char'
share
...
Type erasure techniques
...
I would also consider (similar to void*) the use of "raw storage": char buffer[N].
In C++0x you have std::aligned_storage<Size,Align>::type for this.
You can store anything you want in there, as long as it's small enough and you deal with the alignment properly.
...
Selecting element by data attribute
Is there an easy and straight-forward method to select elements based on their data attribute? For example, select all anchors that has data attribute named customerID which has value of 22 .
...
extract part of a string using bash/cut/split
...gs based on position using numbers:
${MYVAR:3} # Remove the first three chars (leaving 4..end)
${MYVAR::3} # Return the first three characters
${MYVAR:3:5} # The next five characters after removing the first 3 (chars 4-9)
You can also replace particular strings or patterns using:
${MYVAR/sear...
How to create an object for a Django model with a many to many field?
...dd(bar1)
foo.bars.add(bar2)
It generates a whopping total of 7 queries:
SELECT "app_bar"."id", "app_bar"."name" FROM "app_bar" WHERE "app_bar"."id" = 1
SELECT "app_bar"."id", "app_bar"."name" FROM "app_bar" WHERE "app_bar"."id" = 2
INSERT INTO "app_foo" ("name") VALUES ()
SELECT "app_foo_bars"."b...
How to get input type using jquery?
...to now which are checked, and if it is a drop down I need to know which is selected, and I if it is a text/textarea I need to know the values.
...
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 ...