Reading this original article on The Code Project will help you a lot: Visual Representation of SQL Joins. Also check this post: SQL SERVER – Better Performance – LEFT JOIN or NOT IN?. Find original one at: Difference between JOIN and OUTER JOIN in MySQL.
you should put those two dates between single quotes like.. or can use keep in mind that the first date is inclusive, but the second is exclusive, as it effectively is ‘2011/02/27 00:00:00’
If you have a numeric column, all you have to do is use a to_char with the right parameters; this should do the work:
A very easy one for someone, The following insert is giving me the ORA-01722: invalid number why?
EDIT: Left Join will work if emp_mgr_id is null.
There are many formats supported by SQL Server – see the MSDN Books Online on CAST and CONVERT. Most of those formats are dependent on what settings you have – therefore, these settings might work some times – and sometimes not. The way to solve this is to use the (slightly adapted) ISO-8601 date format … Read more
If you found the exact error “The wait operation timed out” then it is likely you have a database call that took longer than expected. This could be due to any number of things: Transient network problem High SQL server load Problem with SAN, RAID, or storage device Deadlock or other form of multiprocess contention … Read more
You use a self join when a table references data in itself. E.g., an Employee table may have a SupervisorID column that points to the employee that is the boss of the current employee. To query the data and get information for both people in one row, you could self join like this:
If you found the exact error “The wait operation timed out” then it is likely you have a database call that took longer than expected. This could be due to any number of things: Transient network problem High SQL server load Problem with SAN, RAID, or storage device Deadlock or other form of multiprocess contention … Read more