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Is there a MySQL option/feature to track history of changes to records?
...i AFTER INSERT ON MyDB.data FOR EACH ROW
INSERT INTO MyDB.data_history SELECT 'insert', NULL, NOW(), d.*
FROM MyDB.data AS d WHERE d.primary_key_column = NEW.primary_key_column;
CREATE TRIGGER MyDB.data__au AFTER UPDATE ON MyDB.data FOR EACH ROW
INSERT INTO MyDB.data_history SELECT 'up...
Can't launch my app in Instruments: At least one target failed to launch
...To change your code signing identity for Xcode 6:
Click on your Project, Select the Target you are Profiling.
Build Settings -> Code Signing -> Code Signing Identity -> Release
Select your iOS developer profile.
Provisioning Profile: Let Xcode pick the correct Provisioning Profile for yo...
Set icon for Android application
...c sizing.
(Android studio)
Go to menu File* → New → Image Assets → select launcher icon → choose image file.
It will automatically re-size.
Done!
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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 |
+...
Binding an enum to a WinForms combo box, and then setting it
...s.DataSource = Enum.GetValues(typeof(Status));
Getting the enum from the selected item
Status status;
Enum.TryParse<Status>(cbStatus.SelectedValue.ToString(), out status);
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improv...
MySQL show current connection info
...e are MYSQL functions you can use. Like this one that resolves the user:
SELECT USER();
This will return something like root@localhost so you get the host and the user.
To get the current database run this statement:
SELECT DATABASE();
Other useful functions can be found here: http://dev.mys...
How do MySQL indexes work?
...be faster to go through the pages one by one (in a database, this is "poor selectivity").
For a 10-page book, it makes no sense to make an index, as you may end up with a 10-page book prefixed by a 5-page index, which is just silly - just scan the 10 pages and be done with it.
The index also needs t...
SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
...result set to update is before running the update (same query, just with a select):
select *
from QuestionTrackings q
inner join QuestionAnswers a
on q.AnswerID = a.AnswerID
where q.QuestionID is null -- and other conditions you might want
Particularly whether each answer id has definitely only 1...
UIButton title text color
... I want a UIButton to be displayed as highlighted:
- (void)changeColorAsUnselection{
[self setTitleColor:[UIColor colorFromHexString:acColorGreyDark]
forState:UIControlStateNormal &
UIControlStateSelected &
UIControlState...
How to show SQL queries run in the Rails console?
...ecord::Relation’s to_sql method:
User.where(:id => 3).to_sql
#=> "SELECT \"users\".* FROM \"users\" WHERE \"users\".\"id\" = 3"
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follo...