大约有 47,000 项符合查询结果（耗时：0.0530秒） [XML]
MySQL Conditional Insert
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If your DBMS does not impose limitations on which table you select from when you execute an insert, try:
INSERT INTO x_table(instance, user, item)
SELECT 919191, 123, 456
FROM dual
WHERE NOT EXISTS (SELECT * FROM x_table
WHERE user = ...
this.setState isn't merging states as I would expect
...do recursive merge.
You can use the value of the current state this.state.selected to construct a new state and then call setState() on that:
var newSelected = _.extend({}, this.state.selected);
newSelected.name = 'Barfoo';
this.setState({ selected: newSelected });
I've used function _.extend() ...
MySQL order by before group by
... table on both the post_author and the max date.
The solution should be:
SELECT p1.*
FROM wp_posts p1
INNER JOIN
(
SELECT max(post_date) MaxPostDate, post_author
FROM wp_posts
WHERE post_status='publish'
AND post_type='post'
GROUP BY post_author
) p2
ON p1.post_author = p...
PreparedStatement IN clause alternatives?
... and cons of each is available here.
The suggested options are:
Prepare SELECT my_column FROM my_table WHERE search_column = ?, execute it for each value and UNION the results client-side. Requires only one prepared statement. Slow and painful.
Prepare SELECT my_column FROM my_table WHERE search_...
SQL query to select dates between two dates
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you should put those two dates between single quotes like..
select Date, TotalAllowance from Calculation where EmployeeId = 1
and Date between '2011/02/25' and '2011/02/27'
or can use
select Date, TotalAllowance from Calculation where EmployeeId = 1
and Da...
如何获取IE (控件)的所有链接（包括Frameset, iframe） - 其他 - 清泛IT社...
来源：新浪博客
IE 顶层 body 节点通过IHTMLElement->get_all 方法无法获取iframe 里面的节点列表：
CComPtr<IHTMLElement> body;
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CComPtr<IDispatch> spDispCollection;
body->get_all(&spDispCollection);复制代码所以要获取iframe/frame(frameset) ...
Is it possible to style a select box? [closed]
I've got an HTML select box that I need to style. I'd prefer to use just CSS but if I have to I'll use jQuery to fill in the gaps.
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Using DISTINCT and COUNT together in a MySQL Query
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use
SELECT COUNT(DISTINCT productId) from table_name WHERE keyword='$keyword'
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Selecting only numeric columns from a data frame
...traightforward, and robust to use on database-back-ended tibbles:
dplyr::select_if(x, is.numeric)
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MySQL “Group By” and “Order By”
I want to be able to select a bunch of rows from a table of e-mails and group them by the from sender. My query looks like this:
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