Tutorial 39 - Truncate Table Video Lecture | Postgresql: A Complete Tutorial - Database Management

hello guys welcome back to love
PostgreSQL in this room I'm gonna tell
you about the truncate table command so
the truncate table is used to delete the
complete data from existing tables what
I mean is that suppose I have a table
and I have thousands and lakhs of record
in it so a model because I want to
delete the complete table or I want to
remove the data of the table without
altering the structure of the table that
is I want all the column names to be
there the structure of the table should
be there but the data inside the table
should be empty so for that I need to
use the truncate table we could also use
the drop table for this but if we would
use a drop table so it would remove the
complete table structure and even the
tables of people to remove and we need
to recreate the table if you want to you
know insert the data again so what I
mean is that just we have a table that
is Sal underscore EMP so in this we have
two recalls now and we have three
columns so it is named pay and she do so
what I mean by truncating is that I need
to delete the two records but I need the
name the pay and the she due to exist so
suppose if I use the drop table on this
then entire table that is the sadness
Cory MP table would be deleted but I've
used the truncate only two records that
is Rahul and Rishi will be deleted and
the name pay and shedule would be still
exist existing and the sad and disco EMP
table would be still existing so for
truncating the table we have a simple
way that is truncate table underscore
EMP just run and you could see we have
no result it means that it has gone
refresh and see I have
thing left so that is the purpose of
truncating in tables so she wanna add
something you not because it does not
have a primary key here so another
simple way of or truncating is that just
right-click and you could see that you
have truncate command here just do yes
and you would see it would delete and
the second option is truncate cascaded
so in case you don't need you don't know
what cascade means you should refer to a
previous tutorial on primary keys
foreign keys and cascading so cascaded
means like if there are some foreign
keys that are associated with this table
so if we delete the information of this
table then the information of that table
should be deleted too so if we use
truncate cascaded that means if there
are foreign keys that are existing on
this table so if you delete in this
table the keys that are associated with
this would also be deleted on the other
table so if I click on class gated you
would see that I get a message or you
show you wish to truncate this table and
all the tables that have fallen key
references to this table so I avoid it
means that if there are any foreign key
references to this table from some other
table then those the gods in that table
would be deleted too so this is all for
the truncate come on thank you for
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