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UPDATE multiple tables in MySQL using LEFT JOIN
...= t1.id
SET t1.col1 = newvalue
WHERE t2.id IS NULL
Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:
SELECT t1.*
FROM t1
WHERE t1.id NOT IN
(
SELECT id
FROM t2
)
See the article in my blog for performance details...
How to create cron job using PHP?
...
Type the following in the linux/ubuntu terminal
crontab -e
select an editor (sometime it asks for the editor)
and this to run for every minute
* * * * * /usr/bin/php path/to/cron.php &> /dev/null
...
How to solve “The specified service has been marked for deletion” error
...ing state. The following procedure worked for me:
open task manager > select services tab > select the service > right click and select "go to process" > right click on the process and select End process
Service should be gone after that
...
SET NOCOUNT ON usage
...OUNT is ON. Depends on client lib implementation in cases when query holds SELECT statements or RPC calls that do select, it may require to disable counting... WHEN disabled, rows are still counted for select statement, but flag DONE_COUNT is set to false. Always read what your client lib suggests s...
android get all contacts
... ContactsContract.Contacts.DISPLAY_NAME
} ;
String selection = null; //Selection criteria
String[] selectionArgs = {}; //Selection criteria
String sortOrder = null; //T...
PostgreSQL DISTINCT ON with different ORDER BY
...llowing approaches:
The general solution that should work in most DBMSs:
SELECT t1.* FROM purchases t1
JOIN (
SELECT address_id, max(purchased_at) max_purchased_at
FROM purchases
WHERE product_id = 1
GROUP BY address_id
) t2
ON t1.address_id = t2.address_id AND t1.purchased_at = t2...
html select option separator
How do you make a separator in a select tag?
14 Answers
14
...
postgresql: INSERT INTO … (SELECT * …)
...ostgres
CREATE TABLE tblA (id serial, time integer);
INSERT INTO tblA
SELECT id, time
FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
AS t(id integer, time integer)
WHERE time > 1000;
TABLE tblA;
id | time
----+------
1 | 5000
2 | 2000
(2 rows)
PostgreSQL has ...
Where do I set my company name?
...
In xCode 7.3 (edit: till 11.3.1) just select top project file and Look in Utilities on Left pane
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How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
... 0.0 NaN 0.0
3 0.0 1.0 2.0 3.0
4 NaN 0.0 NaN NaN
If you want to select the rows that have two or more columns with null value, you run the following:
>>> qty_of_nuls = 2
>>> df.iloc[df[(df.isnull().sum(axis=1) >=qty_of_nuls)].index]
0 1 2 3
1 0.0 NaN 0...