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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...
Difference between natural join and inner join
...INNER JOIN and NATURAL JOIN is the number of columns returned.
Consider:
TableA TableB
+------------+----------+ +--------------------+
|Column1 | Column2 | |Column1 | Column3 |
+-----------------------+ +--------------------+
| 1 ...
Is it possible to for SQL Output clause to return a column not being inserted?
...modifications to my database and I need to migrate the old data to the new tables. For that, I need to fill a table (ReportOptions) taking the data from the original table (Practice), and fill a second intermediate table (PracticeReportOption).
...
MySQL: #126 - Incorrect key file for table
...is can be caused by a full ramdisk when doing things like altering a large table if you have a ramdisk configured. You can temporarily comment out the ramdisk line to allow such operations if you can't increase the size of it.
...
Favourite performance tuning tricks [closed]
...e following...
99% of problems I have seen are caused by putting too many tables in a join. The fix for this is to do half the join (with some of the tables) and cache the results in a temporary table. Then do the rest of the query joining on that temporary table.
Query Optimisation Checklist
...
Django in / not in query
...
table1.objects.exclude(id__in=
table2.objects.filter(your_condition).values_list('id', flat=True))
The exclude function works like the Not operator you where asking for. The attribute flat = True tells to table2 query t...
Most efficient way to determine if a Lua table is empty (contains no entries)?
What's the most efficient way to determine if a table is empty (that is, currently contains neither array-style values nor dict-style values)?
...
Hidden Features of SQL Server
...T clause allows to do this very easily - it allows access to the "virtual" tables called inserted and deleted (like in triggers):
DELETE FROM (table)
OUTPUT deleted.ID, deleted.Description
WHERE (condition)
If you're inserting values into a table which has an INT IDENTITY primary key field, with ...
Hidden Features of MySQL
...t connections, but self compiled binaries often have less of a limit.
Set table_cache to match the number of your open tables and concurrent connections. Watch the open_tables value and if it is growing quickly you will need to increase its size.
Note:
The 2 previous parameters may require a lot...
Change Schema Name Of Table In SQL
I want to change schema name of table Employees in Database. In the current table Employees database schema name is dbo I want to change it to exe . How can I do it ?
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