大约有 47,000 项符合查询结果（耗时：0.0226秒） [XML]
SQL: How to properly check if a record exists
...
It's better to use either of the following:
-- Method 1.
SELECT 1
FROM table_name
WHERE unique_key = value;
-- Method 2.
SELECT COUNT(1)
FROM table_name
WHERE unique_key = value;
The first alternative should give you no result or one result, the second count should be zero or on...
How to check if command line tools is installed
...ars in the Applications directory.
There are also the xcodebuild and xcode-select files in /usr/bin
I need to know if the command line tools is installed.
Is there a command for it?
What can I do to see if XCode CLT is installed and if yes to find the version installed?
...
Ruby on Rails form_for select field with class
I am beating my head against the wall on this one. I want to make a simple select tag using the f.select tag but nothing I do works. I put an example below:
...
How to select an option from drop down using Selenium WebDriver C#?
I was trying for my web test selecting an option. An example can be found here: http://www.tizag.com/phpT/examples/formex.php
...
Indentation shortcuts in Visual Studio
I'm new to Visual Studio 2010 and C#. How can I indent the selected text to left/right by using shortcuts?
8 Answers
...
How do I check if a column is empty or null in MySQL?
...
This will select all rows where some_col is NULL or '' (empty string)
SELECT * FROM table WHERE some_col IS NULL OR some_col = '';
share
|
...
How do I limit the number of rows returned by an Oracle query after ordering?
...Oracle in this answer).
To answer the original question, here's the query:
SELECT *
FROM sometable
ORDER BY name
OFFSET 20 ROWS FETCH NEXT 10 ROWS ONLY;
(For earlier Oracle versions, please refer to other answers in this question)
Examples:
Following examples were quoted from linked page, in th...
How to disable/enable select field using jQuery?
...gt;
<label for="pizza">I would like to order a</label>
<select id="pizza_kind" name="pizza_kind">
<option>(choose one)</option>
<option value="margaritha">Margaritha</option>
<option value="hawai">Hawai</option>
</select>
...
How to make the first option of selected with jQuery
How do I make the first option of selected with jQuery?
27 Answers
27
...
MySQL Insert Where query
...INSERT INTO Users(weight, desiredWeight)
VALUES (160,145)
INSERT using a SELECT statement
INSERT INTO Users(weight, desiredWeight)
SELECT weight, desiredWeight
FROM AnotherTable
WHERE id = 1
share
|
...