SQLite - editing an existing database

[Bert]

I have an existing database called test.db. I know there is a column called "Name" and a column called "Value". There are about 51 rows of data. I've been poring through the help file, goggling like mad and I'm no closer to being able to work with this thing. Outside of today I have about zero experience with SQLite. I know after this project is done I may not work with again for a long time due to other projects in the pipeline.

What I'm looking to do is simply delete some of the data in the values column. In simply trying to run a query I keep running into an error:

no such table

Example script:

#include <SQLite.au3>
#include <SQLite.dll.au3>
#include <File.au3>

Local $hQuery, $aRow, $aNames

_SQLite_Startup()
If @error Then
    MsgBox(16, "SQLite Error", "SQLite3.dll Can't be Loaded!")
    Exit -1
EndIf
ConsoleWrite("_SQLite_LibVersion=" & _SQLite_LibVersion() & @CRLF)

Local $sDbName =   "test.db" ;DB is in the same folder as the script
Local $hDskDb = _SQLite_Open($sDbName) ; Open a permanent disk database - this works fine
_SQLite_Query(-1, "SELECT ROWID,1 FROM Test ORDER BY a;", $hQuery) ;what am I doing wrong here? I get no such table: Test, Name, Value...what do I use here?

If @error Then
    MsgBox(16, "SQLite Error", "Can't open or create a permanent Database!")
    Exit -1
EndIf

; we can use the 3 database as needed by refering to their handle

; close the Dbs we created, in any order
_SQLite_Close($hDskDb)

; we don't really need that DB
FileDelete($sDbName)

_SQLite_Shutdown()

output from the console when I run the script:

_SQLite_LibVersion=3.7.2

! SQLite.au3 Error

--> Function: _SQLite_Query

--> Query: SELECT ROWID,1 FROM Test ORDER BY a;

--> Error: no such table: Test

!>15:08:53 AutoIT3.exe ended.rc:-1

>Exit code: -1 Time: 7.006

What am I doing wrong here?

[JohnQSmith]

Just because the database file is called "test.db" does not necessarily mean the name of the table in the database is called "test".

[JLogan3o13]

You could use something like this to find out the names of all your tables:

SELECT name FROM test
WHERE type='table'
ORDER BY name;

[jchd]

Hi MPH,

Please run the following (after opening a connection with handle $hdb, obviously):

_SQLite_GetTable2d($hdb, "select * from sqlite_master where type = 'table'", $aTables)
_ArrayDisplay($aTables)

You can then see which tables are there and how they were declared (the SQL column).

Edit: JLogan, your query won't work in SQLite.

Edited February 1, 2012 by jchd

[JohnQSmith]

I was just going to offer something to that effect, but had to look it up first.

If you have the sqlite3.exe program, you can do the following.

cmdprompt> sqlite3 test.db

sqlite> .tables
 ... tables names are listed here
sqlite> .exit

cmdprompt>

[JLogan3o13]

I was just updating mine, but jhcd beat me to it. If you don't know the table name, you have to go through the sqlite_master.

[jchd]

Correct. That's where SQLite stores the schema. Granted, it isn't in the most practical form (have to reparse SQL to get full details by program but it's better than nothing).

[Bert]

I'll have to test in the morning for the db is on my work PC

[Bert]

Hi MPH,

Please run the following (after opening a connection with handle $hdb, obviously):

_SQLite_GetTable2d($hdb, "select * from sqlite_master where type = 'table'", $aTables)
_ArrayDisplay($aTables)

You can then see which tables are there and how they were declared (the SQL column).

Edit: JLogan, your query won't work in SQLite.

OK, tried your code. I got a results back and tried each item listed. Still getting the same error : no such table.

expandcollapse popup

#include <SQLite.au3>
#include <SQLite.dll.au3>
#include <File.au3>

Local $hQuery, $aNames, $aTables
Local $iRows, $iColumns, $sMsg

_SQLite_Startup()
If @error Then
    MsgBox(16, "SQLite Error", "SQLite3.dll Can't be Loaded!")
    Exit -1
EndIf
ConsoleWrite("_SQLite_LibVersion=" & _SQLite_LibVersion() & @CRLF)

Local $sDbName =   "test.db" ;DB is in the same folder as the script
Local $hDskDb = _SQLite_Open($sDbName) ; Open a permanent disk database - this works fine
;_SQLite_GetTable($hDskDb, "select * from sqlite_master where type = 'table'", $aTables, $iRows, $iColumns)
;_ArrayDisplay($aTables)
;returned - [0]|type|name|tbl_name|rootpage|sql

;_SQLite_GetTable2d($hDskDb, "select * from sqlite_master where type = 'table'", $aTables, $iRows, $iColumns)
;_ArrayDisplay($aTables)
#cs
Returned:
[0]|5
[1]|type
[2]|name
[3]|tbl_name
[4]|rootpage
[5]|sql
#ce

_SQLite_Query(-1, "SELECT ROWID,1 FROM NAME ORDER BY Name;", $hQuery) ;still doesn't work.

If @error Then
    MsgBox(16, "SQLite Error", @error)
    Exit -1
EndIf

While _SQLite_FetchData($hQuery, $iRows) = $SQLITE_OK
    $sMsg &= $iRows[0]
WEnd
_SQLite_Exec(-1, "DROP TABLE aTest;") ; Remove the table
MsgBox(0, "SQLite", "Get Data using a Query : " & $sMsg)

_SQLite_Close($hDskDb)
FileDelete($sDbName)
_SQLite_Shutdown()


#cs
_SQLite_LibVersion=3.7.2
!   SQLite.au3 Error
--> Function: _SQLite_Query
--> Query:    SELECT ROWID,1 FROM NAME ORDER BY Name;
--> Error:    no such table: NAME

!>08:44:51 AutoIT3.exe ended.rc:-1
>Exit code: -1    Time: 5.749
#ce

Edited February 2, 2012 by MPH

[saywell]

Why not open it in an sqlite browser?

There's a firefox add-on called SQlite manager, which i quite like. Others exist.

You could use this to find out the table structure so you can write programmed edits etc in the future - or use its editing facility to make the occasional ad hoc edit that's no worth writing script for.

William

[jchd]

If you don't get anything back but only headers, it means the DB does actually contain no table, as the first item (table count) of the _SQLite_GetTable shows. The file size doesn't mean much as when dropping a table, pages that were freed are not automatically vaccumed.

There's nothing you can do to reliably "undrop" table(s).

Lastly: stay away of the _SQLite_Query, _SQlite_Step, _SQLite_FetchData sequence. First you have a lot of error handling to code and you also have to finalize the statement. Favor _SQLite_GetTable[2d] instead in a single operation.

Edited February 2, 2012 by jchd

[Bert]

I did manage to edit the thing to the way I needed it. The problem is when I tried to used it in the app the db is used in I found the app simply mad a new db for it didn't like how I modified the first one. I may need more help on this.

[jchd]

If it's something you can share, even privately, I'd be very pleased to help.

If that's private stuff, I warmly recommend you start by downloading and installing SQLite Expert Personal. From there, open your DB and look around. Don't edit things inside without knowing exactly what to do.

FYI, in the existing application, _SQLite_Open should have the existing DB as parameter. Then it won't create a new one. Then it's possible that the app drops tables or does cleanup activities. May be you want to skip that. Anyway, work on a copy.