大约有 47,000 项符合查询结果（耗时：0.0248秒） [XML]
LINQ to SQL: Multiple joins ON multiple Columns. Is this possible?
... from child in context.Childs
where child.Parent.col2 == 4
select new
{
childCol1 = child.col1,
parentCol1 = child.Parent.col1,
};
will generate the query
SELECT [t0].[col1] AS [childCol1], [t1].[col1] AS [parentCol1]
FROM [dbo].[Child] AS [...
JSON encode MySQL results
...
$sth = mysqli_query($conn, "SELECT ...");
$rows = array();
while($r = mysqli_fetch_assoc($sth)) {
$rows[] = $r;
}
print json_encode($rows);
The function json_encode needs PHP >= 5.2 and the php-json package - as mentioned here
NOTE: mysql is dep...
Extracting hours from a DateTime (SQL Server 2005)
...
SELECT DATEPART(HOUR, GETDATE());
DATEPART documentation
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ORACLE 常用日期函数 - ORACLE - 清泛IT论坛，有思想、有深度
...日期。如果给出一负数，返回值日期之前几个月日期。
select add_months(to_date('20150201','yyyymmdd'), -1) from dual
结果：2015/1/1
相应的，加减天数add_days函数是不存在的，直接用+、-即可，例如：
select to_date('20150201','yyyymmdd')+1 from dual
...
MySQL and GROUP_CONCAT() maximum length
...You should use it like this.
SET SESSION group_concat_max_len = 1000000;
select group_concat(column) from table group by column
You can do this even in sharing hosting, but when you use an other session, you need to repeat the SET SESSION command.
...
LEFT OUTER joins in Rails 3
...OUTER JOIN users ON users.id = posts.user_id").
joins(:blog).select
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Python in Xcode 4+?
...
In the menu bar, click “File” → “New” → “New Project…”.
Select “Other” in the left pane, then "External Build System" in the right page, and next click "Next".
Enter the product name, organization name, or organization identifier.
For the “Build Tool” field, type in /usr/l...
Returning anonymous type in C#
...C = new MyDC())
{
var TheQueryFromDB = (....
select new { SomeVariable = ....,
AnotherVariable = ....}
).ToList();
return TheQueryFromDB
.Select(s => (
SomeVariable...
SQL is null and = null [duplicate]
...e t (x int, y int);
insert into t values (null, null), (null, 1), (1, 1);
select 'x = null' as test , x, y from t where x = null
union all
select 'x != null', x, y from t where x != null
union all
select 'not (x = null)', x, y from t where not (x = null)
union all
select 'x = y', x, y from t where ...
Find nearest latitude/longitude with an SQL query
...
SELECT latitude, longitude, SQRT(
POW(69.1 * (latitude - [startlat]), 2) +
POW(69.1 * ([startlng] - longitude) * COS(latitude / 57.3), 2)) AS distance
FROM TableName HAVING distance < 25 ORDER BY distance;
where ...