大约有 40,000 项符合查询结果（耗时：0.0188秒） [XML]
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...
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...
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
...
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...
项目管理实践教程二、源代码控制【Source Control Using VisualSVN Server ...
...，没有任何内容在里面。我会在这个教程的第二部分说明如何迁入源代码。
下面，我们开始安全性设置，在左侧的Users上点击右键：
输入上面的信息，点击OK，我们就创建一个用户了。按照上面的过程，分别添加用户Develo...
Sql Server string to date conversion
...what you're looking for. It wont be hard to adapt:
Declare @d datetime
select @d = getdate()
select @d as OriginalDate,
convert(varchar,@d,100) as ConvertedDate,
100 as FormatValue,
'mon dd yyyy hh:miAM (or PM)' as OutputFormat
union all
select @d,convert(varchar,@d,101),101,'mm/dd/yy'
union al...
Force drop mysql bypassing foreign key constraint
...
If you are using phpmyadmin then this feature is already there.
Select the tables you want to drop
From the dropdown at the bottom of tables list, select drop
A new page will be opened having checkbox at the bottom saying
"Foreign key check", uncheck it.
Confirm the deletion by accepting ...
How can I select from list of values in SQL Server
... would be to use a find an replace with UNION to get the distinct values.
SELECT 1
UNION SELECT 1
UNION SELECT 1
UNION SELECT 2
UNION SELECT 5
UNION SELECT 1
UNION SELECT 6
Applied to your long line of comma delimited text
Find and replace every comma with UNION SELECT
Add a SELECT in front of ...