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MySQL COUNT DISTINCT
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Select
Count(Distinct user_id) As countUsers
, Count(site_id) As countVisits
, site_id As site
From cp_visits
Where ts >= DATE_SUB(NOW(), INTERVAL 1 DAY)
Group By site_id
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How to get a group of toggle buttons to act like radio buttons in WPF?
...ike toggle buttons, but also as radio buttons where only one button can be selected / pressed down at a current time. It also need to have a state where none of the buttons are selected / pressed down.
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jQuery to serialize only elements within a div
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Wouldn't $("#divId").find("select, textarea, input").serialize(); yeild better performance? I imagine the above could get slow if the div had lots of elements, like a table with several rows/columns.
– David Murdoch
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创建增量同步Oracle物化视图问题 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
..._tablename refresh fast on demand start with sysdate next sysdate+1/288 as select * from T_tablename@dblink_name;”。
现在，数据库A上此表的主键约束因主键字段值重复而被disable了，在第三个数据库C上新建这个物化视图却失败，说：“ORA-12014: 表 'T_MV_TE...
Formatting code in Notepad++
...X -> HTML Tidy -> Tidy: Reindent XML
Remember to have the HTML code selected before you do this.
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Select TreeView Node on right click before displaying ContextMenu
I would like to select a WPF TreeView Node on right click, right before the ContextMenu displayed.
11 Answers
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Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT clause?
...pdated) values(null, null);
Query OK, 1 row affected (0.06 sec)
mysql> select * from t5;
+----+---------------------+---------------------+
| id | stamp_created | stamp_updated |
+----+---------------------+---------------------+
| 2 | 2009-04-30 09:44:35 | 2009-04-30 09:44:35 |
+...
Transaction isolation levels relation with locks on table
... writes data and commit/rollback (depending on results). B just executes a SELECT statement to read data. C reads and updates data. All these process work on the same table T.
READ UNCOMMITTED - no lock on the table. You can read data in the table while writing on it. This means A writes data (unc...
String concatenation in MySQL
...most DBMSs use of + or || for concatenation. It uses the CONCAT function:
SELECT CONCAT(first_name, " ", last_name) AS Name FROM test.student
As @eggyal pointed out in comments, you can enable string concatenation with the || operator in MySQL by setting the PIPES_AS_CONCAT SQL mode.
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How to use GROUP BY to concatenate strings in MySQL?
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SELECT id, GROUP_CONCAT(name SEPARATOR ' ') FROM table GROUP BY id;
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
From the link above, GROUP_CONCAT: This function returns a string res...