大约有 40,000 项符合查询结果（耗时：0.0340秒） [XML]
Fast way to discover the row count of a table in PostgreSQL
I need to know the number of rows in a table to calculate a percentage. If the total count is greater than some predefined constant, I will use the constant value. Otherwise, I will use the actual number of rows.
...
MySQL Multiple Joins in one query?
...ally works? Is the second join joining the results of the first join with table 3, or is it joining table 1 with table 3 separately? (i.e., joining table 1 with table 2, and then joining table 1 separately with table 3, then returning it all back?) Does that make sense? I ask because I've been do...
MySql server startup error 'The server quit without updating PID file '
...efix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp
To set up base tables in another folder, or use a different user to run
mysqld, view the help for mysqld_install_db:
mysql_install_db --help
and view the MySQL documentation:
http://dev.mysql.com/doc/refman/5.5/en/mysql-install-db.html...
This Row already belongs to another table error when trying to add rows?
I have a DataTable which has some rows and I am using the select to filter the rows to get a collection of DataRows which I then loop through using foreach and add it to another DataTable, but it is giving me the error "This Row already belongs to another table". Here is the code:
...
MySQL table is marked as crashed and last (automatic?) repair failed
I was repairing this table suddenly server hanged and when I returned back all tables are ok but this one showing 'in use' and when I try to repair it doesn't proceed.
...
JOIN two SELECT statement results
....[# Late], 0) AS [# Late]
FROM
(SELECT ks, COUNT(*) AS '# Tasks' FROM Table GROUP BY ks) t1
LEFT JOIN
(SELECT ks, COUNT(*) AS '# Late' FROM Table WHERE Age > Palt GROUP BY ks) t2
ON (t1.ks = t2.ks);
share
...
Disable Laravel's Eloquent timestamps
... we don't want to add the updated_at / created_at fields to all of our tables as we have a logging class that does all this in more depth for us already.
...
Cast Int to enum in Java
...
@Tarrasch as arrays are mutable, values() must return a copy of the array of elements just in case you happen to change it. Creating this copy each time is relatively expensive.
– Peter Lawrey
Dec 4 '12 at 8:44
...
What are the uses for Cross Join?
...t
size,
color
from
sizes CROSS JOIN colors
Maybe you want a table that contains a row for every minute in the day, and you want to use it to verify that a procedure has executed each minute, so you might cross three tables:
select
hour,
minute
from
hours CROSS JOIN minute...
MFC AfxMessageBox改变标题的几种方法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...工程名的基础上改变标题呢？其实这个标题在资源String Table里就能找到，查找AFX_IDS_APP_TITLE，在这里你就能轻而易举的改变标题了。
注意：如果工程的资源String Table里面没有添加AFX_IDS_APP_TITLE，需要手动添加。
2、修改m_pszA...