SQLite how to open a database from the sqlite> prompt?
lazarus / 16-Databases

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Elmug · 2012-06-26 20:41

Hi everyone,

Have been studying SQLite, but can't seem to find how to OPEN an
existing database while being at the SQLite prompt (the shell
"squlite>" prompt).

I know of starting SQLite from the SYSTEM-shell, by including the
database name.

But if I start the SQLite shell with no database name, how then to
open an existing database?

Also: How to close the database once it has been opened?

Thanks!

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Dick, from the internet · 2012-06-26 21:18

.restore <database name>

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Elmug · 2012-06-26 21:54

Quote from: geno on June 26, 2012, 11:18:28 pm
.restore <database name>

Thanks Geno.

However, I am not sure the .restore command is what I am after, since
I find this definition for it:

.restore Perform a low-level copy of a database file to a database
Common Usage
.restore [database_name] filename
Description
The .restore command performs a low-level copy of a database file into
an open or attached
database. If the database name is not provided, the main database will
be populated. This
command is frequently used to populate an active in-memory database
from a database file.
This command is safe to run against an active source database
(although it may not succeed).
This is the opposite of the .backup command.

I wonder if I got misread?

I thought opening and closing a database from the SQLite prompt would
be an essential thing, but can't find yet how to and surely there must
be a way?

Thanks.

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CaptBill · 2012-06-26 22:10

I don't think you need to "open" a sqlite database per se, unless you
want an in-memory database. You simply issue the sql commands and it
handles any initialization (opening) of the disk file. You sql runs,
gets it's data, and returns it. No "open table" command is necessary,
if my understanding is correct.

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Dick, from the internet · 2012-06-26 23:27

@elmug
yes, I read the help text within sqlite3 as well and it did not show
any method of loading databases (such as mysql's \u or use command);
however, .restore works in a pinch.  Your other option is simply .quit
then reload with the correct database.

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Elmug · 2012-06-26 23:30

Quote from: CaptBill on June 27, 2012, 12:10:31 amI don't think you
need to "open" a sqlite database per se, unless you want an in-memory
database. You simply issue the sql commands and it handles any
initialization (opening) of the disk file. You sql runs, gets it's
data, and returns it. No "open table" command is necessary, if my
understanding is correct.

Hi, and thanks, CaptBill.

I agree that maybe there isn't a dot command or query to open a
database, but am not sure that there wouldn't be any need to
close/open a database, as wished, specially when I have read that one
of the features of SQLite is that it can open more than one database
simultaneously.

So, can one open two databases simultaneously, other than by code?

I came to this issue since I actually started creating databases and
tables using SQLite Administrator, which can connect and disconnect
databases interactively, and naturally assumed this could also be done
by the original SQLite prompt.

It's not an indispensable thing for me right now, though. But it is
great to be aware of what is possible and not.

Thanks.

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Elmug · 2012-06-26 23:31

Quote from: geno on June 27, 2012, 01:27:01 am@elmug
yes, I read the help text within sqlite3 as well and it did not show
any method of loading databases (such as mysql's \u or use command);
however, .restore works in a pinch.  Your other option is simply .quit
then reload with the correct database.

Thanks Geno,

I learned about the restore command, any way. I'm sure I would use it!

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Dick, from the internet · 2012-06-27 00:29

I learned something here as well. At least I had never thought about
it until CaptBill mentioned it; running a sql statement from the
command line - and the output can be put into a text file (or use
another pipe to the command of your choice I suppose)

[geno@geno ~]$ sqlite3 audiocd.dat "select ArtistName From Albums" >>
audiotest

Thanks, ya'll.