Q. What are
temporary tables? when to use them?
Ans. Temporary tables are used to store any data on a temporary basis. in Tempdb.
used to
perform data calculations, data formatting operations for reporting.
create table #table1
(
col1 int,
col2 int,
col3 int
) -- Local temporary
table
insert into #table1 values (10,10,10), (20,20,20)
select * from #table1
Local temp tables:- Local temp
tables are auto removed from temp-db once you close the session.and local temp tables are represent by single # symbol.
-session
means this query windows
create table ##table1
(
col1 int,
col2 int,
col3 int
) -- global temporary
table
insert into ##table1 values (10,10,10), (20,20,20)
select * from ##table1
Global temp tables:- global temp tables are auto removed from temp-db once you close the connection.and global temp tables are represent by ## symbol.
connection
means server level authenticated entry to the database.
ssms >> server name >> connect close ssms: connection close
for better
reuse: permenant tables are recommended.
for faster
performance: temp tables are recommended.
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