大约有 42,000 项符合查询结果（耗时：0.0142秒） [XML]
ROW_NUMBER() in MySQL
...asy, but actually it kind of isn't).
I often plump for a null-self-join:
SELECT t0.col3
FROM table AS t0
LEFT JOIN table AS t1 ON t0.col1=t1.col1 AND t0.col2=t1.col2 AND t1.col3>t0.col3
WHERE t1.col1 IS NULL;
“Get the rows in the table for which no other row with matching col1,col2 has a hi...
What's a quick way to comment/uncomment lines in Vim?
...
For those tasks I use most of the time block selection.
Put your cursor on the first # character, press CtrlV (or CtrlQ for gVim), and go down until the last commented line and press x, that will delete all the # characters vertically.
For commenting a block of text i...
Oracle nvarchar和varchar相互转换、联合查询 - 数据库(内核) - 清泛网 - ...
...tatype isNVARCHAR2.
（A表字段c_xxx:varchar，B表c_xxx:nvarchar）
select translate(c_xxx USING NCHAR_CS) from A
union all
select c_xxx from B
或者
select c_xxx from A
union all
select translate(c_xxx USING CHAR_CS) from B
注意：translate函数括号中没有逗号。
1、...
nvarchar和varchar相互转换、联合查询 - ORACLE - 清泛IT论坛，有思想、有深度
...atype is NVARCHAR2.
（A表字段c_xxx:varchar，B表c_xxx:nvarchar）
select translate(c_xxx USING NCHAR_CS) from A
union all
select c_xxx from B
或者
select c_xxx from A
union all
select translate(c_xxx USING CHAR_CS) from B
注意：translate函数括号中没有逗号。
1、...
How to combine date from one field with time from another field - MS SQL Server
...ro (base date: January 1, 1900)
Adding them returns the correct result.
SELECT Combined = MyDate + MyTime FROM MyTable
Rationale (kudos to ErikE/dnolan)
It works like this due to the way the date is stored as two 4-byte
Integers with the left 4-bytes being the date and the right
4-bytes...
How to export query result to csv in Oracle SQL Developer?
...worksheet toolbar)
That's it.
Method 2
Run a query
Right click and select unload.
Update. In Sql Developer Version 3.0.04 unload has been changed to export
Thanks to Janis Peisenieks for pointing this out
Revised screen shot for SQL Developer Version 3.0.04
From the format drop down...
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...
LINQ Aggregate algorithm explained
...ggregate help readability? In general I love LINQ because I think .Where, .Select, .OrderBy and so on greatly helps readability (if you avoid inlined hierarhical .Selects). Aggregate has to be in Linq for completeness reasons but personally I am not so convinced that .Aggregate adds readability comp...
WITH CHECK ADD CONSTRAINT followed by CHECK CONSTRAINT vs. ADD CONSTRAINT
...CREATE TABLE T2 (FKID INT, SomeOtherVal CHAR(2));
INSERT T1 (ID, SomeVal) SELECT 1, 'A';
INSERT T1 (ID, SomeVal) SELECT 2, 'B';
INSERT T2 (FKID, SomeOtherVal) SELECT 1, 'A1';
INSERT T2 (FKID, SomeOtherVal) SELECT 1, 'A2';
INSERT T2 (FKID, SomeOtherVal) SELECT 2, 'B1';
INSERT T2 (FKID, SomeOtherVal...
Emacs bulk indent for Python
...
I use the following snippet. On tab when the selection is inactive, it indents the current line (as it normally does); when the selection is inactive, it indents the whole region to the right.
(defun my-python-tab-command (&optional _)
"If the region is active, s...