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Can hash tables really be O(1)?
...TW - concrete example - Visual C++'s std::hash of textual keys combines 10 characters evenly spaced along the text into the hash value, so it's O(1) regardless of text length (but massively more collision prone than GCC!). Separately, claims of O(1) have another assumption (normally correctly) that...
Can I create a One-Time-Use Function in a Script or Stored Procedure?
... create temp stored procedures like:
create procedure #mytemp as
begin
select getdate() into #mytemptable;
end
in an SQL script, but not functions. You could have the proc store it's result in a temp table though, then use that information later in the script ..
...
Accessing an SQLite Database in Swift
...pared statement: \(errmsg)")
}
statement = nil
Prepare new statement for selecting values from table and loop through retrieving the values:
if sqlite3_prepare_v2(db, "select id, name from test", -1, &statement, nil) != SQLITE_OK {
let errmsg = String(cString: sqlite3_errmsg(db)!)
pri...
How to map calculated properties with JPA and Hibernate
...e float finalPrice;
Or even complex queries on other tables:
@Formula("(select min(o.creation_date) from Orders o where o.customer_id = id)")
private Date firstOrderDate;
Where id is the id of the current entity.
The following blog post is worth the read: Hibernate Derived Properties - Perform...
MySQL复制的概述、安装、故障、技巧、工具 - 数据库(内核) - 清泛网 - 专注...
...表可以使用不同的键类型。比如主服务器用InnoDB，键用VARCHAR的话节省空间，从服务器使用MyISAM，键用CHAR提高速度，因为MyISAM有静态表一说。
主从服务器中的表可以使用不同的索引。主服务器主要用来应付写操作，所以除了主...
TSQL - Cast string to integer or return default value
...ing
DECLARE @Test TABLE(Value nvarchar(50)) -- Result
INSERT INTO @Test SELECT '1234' -- 1234
INSERT INTO @Test SELECT '1,234' -- 1234
INSERT INTO @Test SELECT '1234.0' -- 1234
INSERT INTO @Test SELECT '-1234' -- -1234
INSERT INTO @Test SELECT '$1234' ...
What is the intent of the methods getItem and getItemId in the Android class BaseAdapter?
... ListView item, it's that simple. When the system notifies you of the user selection, you receive three identifying variables to tell you what was selected:
a reference to the view itself,
its numeric position in the list,
this long you attached to the individual elements.
It's up to you to deci...
Autocomplete applying value not label to textbox
...
The default behavior of the select event is to update the input with ui.item.value. This code runs after your event handler.
Simply return false or call event.preventDefault() to prevent this from occurring. I would also recommend doing something simi...
How to use z-index in svg elements?
...
d3.selection.prototype.moveToFront = function() { return this.each(function() { this.parentNode.appendChild(this); }); }; And then you can say selection.moveToFront() via stackoverflow.com/questions/14167863/…
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How to select the row with the maximum value in each group
In a dataset with multiple observations for each subject I want to take a subset with only the maximum data value for each record. For example, with a following dataset:
...