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What's the difference between RANK() and DENSE_RANK() functions in oracle?
...s a simple test script you can play with to see what happens:
with q as (
select 10 deptno, 'rrr' empname, 10000.00 sal from dual union all
select 11, 'nnn', 20000.00 from dual union all
select 11, 'mmm', 5000.00 from dual union all
select 12, 'kkk', 30000 from dual union all
select 10, 'fff', 4000...
Favourite performance tuning tricks [closed]
...n-optimal query plan
Break up the Join
Can you break up the join?
Pre-select foreign keys into a temporary table
Do half the join and put results in a temporary table
Are you using the right kind of temporary table?
#temp tables may perform much better than @table variables with large volum...
How to convert DateTime to VarChar
...yDateTime DATETIME
SET @myDateTime = '2008-05-03'
--
-- Convert string
--
SELECT LEFT(CONVERT(VARCHAR, @myDateTime, 120), 10)
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How to perform a mysqldump without a password prompt?
...and in no case the root user. It can be done like this: GRANT LOCK TABLES, SELECT ON *.* TO 'BACKUPUSER'@'%' IDENTIFIED BY 'PASSWORD';
– gadjou
Feb 21 '17 at 8:34
...
What is the most ridiculous pessimization you've seen? [closed]
...nearly all their tables have an associated archive table, and most queries select from views that UNION the pairs of tables. Performance is as you would expect!
– Tony Andrews
Mar 26 '09 at 13:32
...
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
...Shouldn't the threads in the connection pool be kept active by firing the "select 1" validation query? Why would they get closed by prolonged inactivity when we have set the evictor to run at shorter time intervals than the mysql server timeout?
– Farhad
Sep 2 ...
ERROR 2006 (HY000): MySQL server has gone away
...L/MariaDB server.
Double check the value was set properly by:
mysql -sve "SELECT @@max_allowed_packet" # or:
mysql -sve "SHOW VARIABLES LIKE 'max_allowed_packet'"
You got a timeout from the TCP/IP connection on the client side.
Solution: Increase wait_timeout variable.
You tried to run a query a...
Get the week start date and week end date from week number
...y other weird value to test it */
DECLARE @d DATETIME
SET @d = GETDATE()
SELECT
@d ThatDate,
DATEADD(dd, 0 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Monday,
DATEADD(dd, 6 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Sunday
...
error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' — Miss
...ate to where your mysql.sock file is located
Right click on the file and select Make Link
Rename the Link File to mysqld.sock then Right click on the file and Cut it
Go to /var/run and create a folder called mysqld and enter it
Now right click and Paste the Link File
Voila! You will now have a mys...
【AI2+AI】人工智能舞姿识别App - 创客硬件开发 - 清泛IT社区，为创新赋能！
...可以帮助我们提高舞蹈技巧吗？在这个项目中，你将学习如何使用新的AI技术PoseNet来跟踪身体的关键点，创建骨骼模型，并开发一些基本方法来量化、测量和识别一些舞蹈动作。1. 项目简介你喜欢跳舞吗？你擅长吗？你想要提高...