大约有 40,000 项符合查询结果（耗时：0.0201秒） [XML]
How do I get the size of a java.sql.ResultSet?
...
Do a SELECT COUNT(*) FROM ... query instead.
OR
int size =0;
if (rs != null)
{
rs.last(); // moves cursor to the last row
size = rs.getRow(); // get row id
}
In either of the case, you won't have to loop over the enti...
Get Specific Columns Using “With()” Function in Laravel Eloquent
... like
Post::with(array('user'=>function($query){
$query->select('id','username');
}))->get();
It will only select id and username from other table. I hope this will help others.
Remember that the primary key (id in this case) needs to be the first param in the
$query->s...
What is the use of the square brackets [] in sql statements?
...
sql also uses square brackets in the like-operator of a select query to limit results using regular expressions. codeproject.com/Articles/33941/SQL-LIKE-Operator
– Jens Frandsen
Sep 4 '13 at 18:49
...
Equals(=) vs. LIKE
... can produce results different from the = comparison operator:
mysql> SELECT 'ä' LIKE 'ae' COLLATE latin1_german2_ci;
+-----------------------------------------+
| 'ä' LIKE 'ae' COLLATE latin1_german2_ci |
+-----------------------------------------+
| 0 |...
Visual Studio : short cut Key : Duplicate Line
...ure is now built-in in VS2017: Ctrl + E, V duplicates a line if nothing is selected, or duplicates selection. You can assign it to a different key combination, or find it in the menu:
See this reference for more information.
Pre VS2017, built-in method using clipboard
As @cand mentioned, you ca...
Setting the selected value on a Django forms.ChoiceField
...t hand, but this Q/A comes up for searches related to trying to assign the selected value to a ChoiceField.
If you have already called super().__init__ in your Form class, you should update the form.initial dictionary, not the field.initial property. If you study form.initial (e.g. print self.init...
SQL Server indexes - ascending or descending, what difference does it make?
...TE INDEX ix_index ON mytable (col1, col2 DESC);
can be used for either:
SELECT *
FROM mytable
ORDER BY
col1, col2 DESC
or:
SELECT *
FROM mytable
ORDER BY
col1 DESC, col2
, but not for:
SELECT *
FROM mytable
ORDER BY
col1, col2
An index on a single colum...
Joining three tables using MySQL
...
Simply use:
select s.name "Student", c.name "Course"
from student s, bridge b, course c
where b.sid = s.sid and b.cid = c.cid
share
|
...
oracle group 取每组第一条 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...type字段分组,code排序,取出每组中的第一条记录方法一：select type,min(code) from group_infogro...Oracle查询：取出每组中的第一条记录
按type字段分组，code排序，取出每组中的第一条记录：
方法一：
select type,min(code) from group_info grou...
Comparing Dates in Oracle SQL
...r by using the built-in TO_DATE() function, or a date literal.
TO_DATE()
select employee_id
from employee
where employee_date_hired > to_date('31-DEC-95','DD-MON-YY')
This method has a few unnecessary pitfalls
As a_horse_with_no_name noted in the comments, DEC, doesn't necessarily mean D...