大约有 47,000 项符合查询结果（耗时：0.0444秒） [XML]
Form inline inside a form horizontal in twitter bootstrap?
...abel class="control-label">Date of birth:</label>
<div>
<select class="form-control form-control-inline" name="year"> ... </select>
<select class="form-control form-control-inline" name="month"> ... </select>
<select class="form-control form-control-inline" ...
Does the join order matter in SQL?
...t matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.
For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.
First, outer joins are not commutative, so a LEFT JOIN b is no...
find vs find_by vs where
...irb(main):037:0> @kit = Kit.find_by(number: "3456")
Kit Load (0.9ms) SELECT "kits".* FROM "kits" WHERE "kits"."number" =
'3456' LIMIT 1
=> #<Kit id: 1, number: "3456", created_at: "2015-05-12 06:10:56",
updated_at: "2015-05-12 06:10:56", job_id: nil>
irb(main):038:0> @kit.upd...
PostgreSQL DISTINCT ON with different ORDER BY
...llowing approaches:
The general solution that should work in most DBMSs:
SELECT t1.* FROM purchases t1
JOIN (
SELECT address_id, max(purchased_at) max_purchased_at
FROM purchases
WHERE product_id = 1
GROUP BY address_id
) t2
ON t1.address_id = t2.address_id AND t1.purchased_at = t2...
Get the new record primary key ID from MySQL insert query?
...
Eg:
INSERT INTO table_name (col1, col2,...) VALUES ('val1', 'val2'...);
SELECT LAST_INSERT_ID();
This will get you back the PRIMARY KEY value of the last row that you inserted:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returne...
Fastest check if row exists in PostgreSQL
...
Use the EXISTS key word for TRUE / FALSE return:
select exists(select 1 from contact where id=12)
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Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc
I've heard that SELECT * is generally bad practice to use when writing SQL commands because it is more efficient to SELECT columns you specifically need.
...
set gvim font in .vimrc file
...tart a graphical vim session.
Do :e $MYGVIMRC Enter
Use the graphical font selection dialog to select a font.
Type :set guifont= Tab Enter.
Type G o to start a new line at the end of the file.
Type Ctrl+R followed by :.
The command in step 6 will insert the contents of the : special register
whic...
XPath OR operator for different nodes
...
If you want to select only one of two nodes with union operator, you can use this solution:
(//bookstore/book/title | //bookstore/city/zipcode/title)[1]
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MySQL select where column is not empty
In MySQL, can I select columns only where something exists?
13 Answers
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