大约有 37,000 项符合查询结果（耗时：0.0313秒） [XML]
Best way to clear a PHP array's values
...hing more powerful use unset since it also will clear $foo from the symbol table, if you need the array later on just instantiate it again.
unset($foo); // $foo is gone
$foo = array(); // $foo is here again
share
...
TSQL - Cast string to integer or return default value
...> 2147483647 RETURN NULL
RETURN @I
END
GO
-- Testing
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' ...
MySQL order by before group by
...hor is to use a subquery to return the max date and then join that to your 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'
...
Output array to CSV in Ruby
...
I pulled in a CSV file using CSV.table, did some manipulations, got rid of some columns, and now I want to spool the resulting Array of Hashes out again as CSV (really tab-delimited). How to? gist.github.com/4647196
– tamouse
...
Can you get the column names from a SqlDataReader?
...case unless I used quotes around the column name. SELECT id AS "MyId" FROM table;
– styfle
Jul 13 '13 at 0:02
sir its ...
What is an ORM, how does it work, and how should I use one? [closed]
...(book);
}
With an ORM library, it would look like this:
book_list = BookTable.query(author="Linus");
The mechanical part is taken care of automatically via the ORM library.
Pros and Cons
Using ORM saves a lot of time because:
DRY: You write your data model in only one place, and it's easier...
How to set default values in Rails?
... If you know you'll always want that default value for that column on that table, setting them in a DB migration file is the easiest way:
class SetDefault < ActiveRecord::Migration
def self.up
change_column :people, :last_name, :type, :default => "Doe"
end
def self.down
# You c...
SQL SELECT WHERE field contains words
...
Rather slow, but working method to include any of words:
SELECT * FROM mytable
WHERE column1 LIKE '%word1%'
OR column1 LIKE '%word2%'
OR column1 LIKE '%word3%'
If you need all words to be present, use this:
SELECT * FROM mytable
WHERE column1 LIKE '%word1%'
AND column1 LIKE '%word2%'
...
Order discrete x scale by frequency/value
...
ggplot(mtcars, aes(factor(cyl))) + geom_bar()
# Manual levels
cyl_table <- table(mtcars$cyl)
cyl_levels <- names(cyl_table)[order(cyl_table)]
mtcars$cyl2 <- factor(mtcars$cyl, levels = cyl_levels)
# Just to be clear, the above line is no different than:
# mtcars$cyl2 <- factor(m...
Floating elements within a div, floats outside of div. Why?
...to support old browsers, or using other block-level displays like display: table.
Solution: BFC roots
There is an exception to the problematic behavior defined at the beginning: if a block element establishes a Block Formatting Context (is a BFC root), then it will also wrap its floating contents....