大约有 40,000 项符合查询结果（耗时：0.0215秒） [XML]
Using LIMIT within GROUP BY to get N results per group?
...to get all years into a single column, grouped by id and ordered by rate:
SELECT id, GROUP_CONCAT(year ORDER BY rate DESC) grouped_year
FROM yourtable
GROUP BY id
Result:
-----------------------------------------------------------
| ID | GROUPED_YEAR |...
When to use Hadoop, HBase, Hive and Pig?
...
Consider that you work with RDBMS and have to select what to use - full table scans, or index access - but only one of them.
If you select full table scan - use hive. If index access - HBase.
s...
MySQL Workbench Dark Theme
...there somewhere else within the Workbench GUI that I need to go to see and select a theme? Besides under "Edit->Preferences-> Fonts & Colors
– edo101
May 7 at 18:54
...
Combined area of overlapping circles
...d four circles (midpoints and radius) and had to calculate the area of the union of these circles.
14 Answers
...
Oracle PL/SQL - How to create a simple array variable?
... INDEX BY PLS_INTEGER;
employee_array employee_arraytype;
BEGIN
SELECT *
BULK COLLECT INTO employee_array
FROM employee
WHERE department = 10;
--
FOR i IN employee_array.FIRST .. employee_array.LAST
LOOP
-- Do something
END LOOP;
END;
The associative arra...
'0000-00-00 00:00:00' can not be represented as java.sql.Timestamp error
...o update the values, or while these modifications take place, you can do a select using a case/when.
SELECT CASE ModificationDate WHEN '0000-00-00 00:00:00' THEN '1970-01-01 01:00:00' ELSE ModificationDate END AS ModificationDate FROM Project WHERE projectId=1;
...
JOIN queries vs multiple queries
...han several queries? (You run your main query, and then you run many other SELECTs based on the results from your main query)
...
Interfacing with structs and anonymous unions with c2hs
...e;
monome_event_type_t event_type;
/* __extension__ for anonymous unions in gcc */
__extension__ union {
struct me_grid {
unsigned int x;
unsigned int y;
} grid;
struct me_encoder {
unsigned int number;
int delta;
...
How to fix “Incorrect string value” errors?
...ify that the tables where the data is stored have the utf8 character set:
SELECT
`tables`.`TABLE_NAME`,
`collations`.`character_set_name`
FROM
`information_schema`.`TABLES` AS `tables`,
`information_schema`.`COLLATION_CHARACTER_SET_APPLICABILITY` AS `collations`
WHERE
`tables`.`table_sche...
Create boolean column in MySQL with false as default value?
... into mytable () values ();
Query OK, 1 row affected (0.00 sec)
mysql> select * from mytable;
+--------+
| mybool |
+--------+
| 0 |
+--------+
1 row in set (0.00 sec)
FYI: My test was done on the following version of MySQL:
mysql> select version();
+----------------+
| version() ...