大约有 47,000 项符合查询结果（耗时：0.0359秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
Remove border radius from Select tag in bootstrap 3
...s gone, you have to add back in the arrow that visually differentiates the select from the input. Note: appearance is not supported in IE.
Working example: https://jsfiddle.net/gs2q1c7p/
select:not([multiple]) {
-webkit-appearance: none;
-moz-appearance: none;
background-positio...
How to set selected value of jquery select2?
This belong to codes prior to select2 version 4
28 Answers
28
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T-SQL: Deleting all duplicate rows but keeping one [duplicate]
... I do not care about that. I still need to keep one of these rows however. SELECT DISTINCT won't work because it operates on all columns and I need to suppress duplicates based on the key columns.
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How to select all records from one table that do not exist in another table?
...
SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 wi...
jQuery UI Tabs - How to Get Currently Selected Tab Index
...answer is there - use ui.index property to get the current index in the tabselect event.....
– redsquare
Nov 5 '09 at 12:27
17
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Select2 dropdown but allow new values by user?
I want to have a dropdown with a set of values but also allow the user to "select" a new value not listed there.
9 Answers...
SQL Server CTE and recursion example
...The query finds all root nodes as described by WHERE ManagerID IS NULL
SELECT EmployeeID, FirstName, LastName, ManagerID, 1
FROM Employees
WHERE ManagerID IS NULL
-->>>>>>>>>>Block 1>>>>>>>>>>>>>>>>>
UNI...
Why are Where and Select outperforming just Select?
...
Select iterates once over the entire set and, for each item, performs a conditional branch (checking for validity) and a + operation.
Where+Select creates an iterator that skips invalid elements (doesn't yield them), perform...
Is there a way to access the “previous row” value in a SELECT statement?
...d to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) ...