Most applications use a database, and there are many excellent database engines to choose from, both free and commercial. SQLite is a small C library that has several advantages. It is open source, free, cross-platform, fast, reliable, and well supported. I had a Delphi 7 application using Sqlite 2.0. There are various wrappers available for Delphi, and around 18 months ago I tried all the ones I could get my hands on. Although several of them were of good quality, I found myself running into bugs caused by the complexity of implementing Borland’s TDataset and related database components. Since I didn’t require databinding, I chose a wrapper that implemented very simple access to Sqlite – it was written by Ben Hochstrasser and amended by Pablo Pissanetzky. An advantage for me was that I could easily see what the wrapper did and make my own amendments. I actually made rather a lot of changes, adding basic transaction support and implementing a crude dataset based on a TList. Despite its simplicity, I found it effective and reliable.
The main author of Sqlite, Dr D Richard Hipp, has since released Sqlite 3.0. This adds some useful features, including BLOB support and the ability to create tables that support case-insensitive comparisons. I decided to update my wrapper for Sqlite 3.0. This meant changing the code from using SQLite’s callback interface to use Sqlite3_Prepare and Sqlite3_Step instead (see the description of the Sqlite C interface). Most of the code written by Ben and Pablo has now gone, which I say not to demean their efforts, but to emphasise their innocence. I’ve also had a go at adding BLOB support. The new wrapper is not yet extensively tested, but so far it is working well.
I’m now offering the wrapper for download. You’re welcome to use it, although naturally it comes with no warranty. I’d be grateful for any comments, bug reports or improvements, though I’d like to keep the wrapper simple. Note this is for Delphi 7, not Delphi .NET (though I’ve also used Sqlite with .NET – see here).
More about the wrapper
This wrapper has two units and three main classes. Sqlite3.pas has the external declarations for sqlite3.dll. I’ve included a binary build of sqlite3.dll, made with Visual C++ 2003. It should work with other builds, so you can upgrade to later versions of the DLL without making changes to the wrapper (unless the Sqlite API itself changes).
Sqlitetable3.pas implements three classes, ESqliteException, TSqliteDatabase and TSqliteTable. Currently TSqliteDatabase has the following methods:
GetTable: execute an SQL query and return a resultset as a TSqliteTable.
ExecSQL: execute an SQL query that does not return data.
UpdateBlob: Update a blob field with data from a TStream object.
BeginTransaction, Commit, Rollback: sends SQL statements for transaction support.
TableExists: Returns true if the specified table exists in the database.
There is also an IsTransactionOpen property.
TSqliteTable represents a resultset. It maintains no link to the source database, so it is disconnected: you can keep a TSqliteTable in memory after freeing the source TSqliteDatabase. When created it is set to the first row. Navigate the resultset using Next and Previous, until EOF is True. At BOF the resultset is on the first row, but at EOF there is no valid row. RowCount retrieves the number of rows, which may be zero. To retrieve data, first use FieldIndex to get the index number of a particular field. Then use the appropriate Field… method to get the value: FieldAsString, FieldAsInteger, FieldAsDouble, FieldAsBlob or FieldAsBlobText. For other datatypes such as Currency or TDateTime, you currently need to convert to String or one of the other types – I’m planning to add some more types soon. I’ve not tested the Blob functionality extensively. Since the entire resultset must fit in memory, be cautious about retrieving large resultsets or resultsets with large amounts of Blob data.
Currently the only way to determine if a field contains a null value is with the FieldIsNull method. The other methods return zero, false or empty strings for null values.
I will be publising a basic tutorial on using the wrapper in the UK magazine PC Plus. I will also keep this page up-to-date with the latest version.
Update 19 February 2005: I’ve updated the wrapper for Sqlite 3.1.2. This changes the way column names are returned, so I’ve added a call to set the Pragma full_column_names on. I’ve also amended the field type detection to use the actual type when the declared type is not available, and added the utility function TableExists. The test application now shows a possible way to load, save and display images in a Sqlite database.
Update 15 August 2005: Thanks to Lukas Gebauer who has made the wrapper compatible with Delphi 4+ and added some new methods. See the readme for details. I’ve also followed Lukas’s suggestion in removing FieldAsBool – he points out that it is not a natural sqlite3 type. If this causes problems for anyone, let me know. I’ve left the previous version available for download just in case. Finally, I’ve included a Visual C++ 2003 release build of Sqlite3 version 3.2.2.
Update 27 August 2007: Thanks to Marek Janáč who emailed me to say that the wrapper did not work with the latest Sqlite3 dll (3.4.2). The problem was that Sqlite now requires pathnames to be in UTF8 format when the path contains accented characters. I’ve made a small change to fix this. I’ve also included a new MSVC 6.0 build of the DLL. Finally, I’ve created a repository for the wrapper here:
https://www.itwriting.com/repos/sqlitewrapper/trunk
Update 16 October 2008: Quick update to get Delphi 2009 compatibility – not properly Unicode-enabled though, yet.
Update 4 February 2011: Added support for SQLite backup API. Updated DLL to Sqlite 3.7.5. Compiled with VC++ 10 but with static linking to avoid runtime dependencies.
Update 10 February 2011: Created new Unicode version. This has not been extensively tested, and requires Delphi 2009 or higher on Windows. Need to make this a single code base across all versions. Removed BindData method pending review for Unicode. Modified demo project to add simple navigation. You can download the Unicode version here.
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Links
Download the Simple Delphi Wrapper
Other Sqlite wrappers including some for Delphi
My notes on using Sqlite 2 with Delphi, .NET and Java
My interview with the main author of Sqlite, Dr D Richard Hipp
tim, that was my error, sorry.
I was using Access (mdb) base, and there was something like this:
ADOQuery1:=’Select * from Table1′;
Adoquery.Recno:=492;
// —
Is there something like RecNo? Maybe, i must always to use?:
key:=492;
Select key From Table1
This is just stupid-easy to use. It’s a complete implementation, it works flawlessly, and it doesn’t bloat out your app with a ton of TDataSet-related cruft… you just saved me a lot of time. 🙂
Thank you!
I’ve been using this simple wrapper for years in my own personal projects and just wanted to say thanks. I also agree with the above commenter, the TDataSet stuff has no place in the Sqlite way of doing things so thanks again for leaving it out!
My company has just released a new SQLite3 wrapper and framework. It’s all Open Source, released under the “SQLite3 blessing” licence.
http://blog.synopse.info/category/Open-Source-Projects/SQLite3-Framework
It is not based on your work, but I have to confess that it was a starting point to find how to access the SQLite3 from Delphi.
Our own wrapper in embedded into Pascal unit file (no dll is needed), and is does much more than just wrap it.
The Synopse SQLite3 database Framework interfaces the SQlite3 database engine into pure Delphi code: database access, User Interface generation, security, i18n are handled in a safe and fast Client/Server AJAX/RESTful model.
I am about to try it with Delphi 2010 E.
I saw the notes about Unicode, thanks for the warning.
Regarding Blobs: According to SqLite, any sqlite(3) field can hold a blob. The size paramter will be ignored if you put more data into a field than it was set for with i.e. varchar(xx)
I’ll let you know about my 2010 success
(or failure)
I like the ease of use of the wrapper. But I encountered a performance problem.
I tried to insert one million records by using the sample project. It took about 2 minutes! Is there any method to speed it up? Thanks!
@Lewis
Yes – wrap the inserts in a transaction.
Tim
Tim, I already wrap it in a transaction. Here is what I did:
———————–
sldb.BeginTransaction;
for index := 0 to 1000000 do
begin
sSQL := ‘INSERT INTO testtable(Name,OtherID,Number,Notes) VALUES (“‘+IntToStr(index)+'”,12,4758.3265,”More notes”);’;
sldb.ExecSQL(sSQL);
end;
sldb.Commit;
———————–
I also tried to change the “cache_size”, “synchronous” options but they didn’t help.
Hi Tim,
First of all, fantastic work !
Secondly, I was trying to vacuum the sqlite db via the “framework”. Very few can be found on this (in general) and added a procedure :
___________
procedure TSQLiteDatabase.Vacuum;
var
Stmt: TSQLiteStmt;
Msg: PAnsiChar;
NextSQLStatement: PAnsiChar;
SQL : string;
begin
SQL := ‘VACUUM;’;
Msg := nil;
try
if Sqlite3_Prepare_v2(self.fDB, PAnsiChar(SQL), -1, Stmt, NextSQLStatement)
SQLITE_OK then
RaiseError(‘Could not prepare SQL statement’, SQL);
if (Stmt = nil) then
RaiseError(‘Could not prepare SQL statement’, SQL);
DoQuery(SQL);
finally
if Assigned(Stmt) then
Sqlite3_Finalize(stmt);
if Assigned(Msg) then
SQLite3_Free(Msg);
end;
end;
____
The good news is that I get no errors from the prepare and in general. The bad news is that the db is not vacuumed !
Any ideas ? (non-sql statement via sql statement ?)
Thanks !
Cheers,
Geert
Geert
As far as I can tell it should work. Any clues here?
Tim
Hi Tim,
Both conditions are OK and still no compression.
I will have a closer look at this after the holidays.
BTW best wishes for 2010 for all !
Thanks !
Cheers,
Geert
Geert, about the speed of insertion, try preparing the SQL statement, and bind the field values as parameters. It should be faster, since the SQL statement will be compiled only once by the SQLite3 database engine.
According to most benchmark and to the source code, insertion was never meant to be fast with SQLite3, even with transactions: ACID and journalized write are always expensive tasks. Dedicated code should be most valuable for such tasks (did you try memory mapped files, they are great for fast access to great amount of data from Delphi code).
[Delphi 2010]
Because SQLiteTable3.pas row 854 ->sqlite3_bind_parameter_index didn´t find parameter from list
I changed string to ansistring of name.
TSQliteParam = class
public
name: Ansistring; // changed from string to AnsiString
valuetype: integer;
valueinteger: int64;
valuefloat: double;
valuedata: string;
end;
Main problem seems to be in sqlite3.dll for data type REAL. After insert statement with Value = “1,25” a problem occurs. Germans write “1,25”, english is it written “1.25”. If REAL value is read, it is cut at the coma, so the returned value is 1 instead of (german) 1,25. Is there a possibility to change REAL value handling in sqlite3.dll?
Greetings
Michael Wollert
Hello,
is a possible to use .import with/in execsql().
I received error. Now I can import file into table.
regards.
I am using the Simple Delphi Wrapper for SQLite3 with Delphi 2010. I am using it for a database that is created and maintained by others and I have no ability to redefine its individual fields. I have run into a problem with trying to read a field that has been defined as SMALLINT. Is there any way to read this field with the wrapper?
Lew, there is a Embarcadero supported download for registered users that supports Sqlite (and a few other) databases, natively in Delphi 2010. Maybe that would solve your issue.
Thanks. I’ll look into it.
Hi Tim
I try to use your wrapper with Delphi 2010.
I modified the example to use my SQLite database. Using the SQL statement ‘Select * From Mp3Record’ works fine, but when I try to select specific records like
‘Select * From Mp3Record Where Genre=’ + chr(39) + ‘Disco’ + chr(39
I get the following error:
‘Error executing SQL. Error[1]: SQL error or missing database
“Select * From Mp3Record Where Genre=’Disco'”: no such collation sequence: SYSTEMNOCASE’ occured.
But that’s a correct SQL statement.
How do I ‘filter’ a query?
Thanks in advance!
Micha
Hey guys,
I made few changes on the wrapper to make it compatible with Delphi 2010
You may download the modified version from:
http://www.wishapps.com/sqlitewrapper/sqlite-delphi-2010.rar
brian, I have looked for the download you mentioned, but I can’t find it. Have you got a link or a name for the download?
This is a very good tool.
I have to access to a special sqlite-db with many TEXT colums, and I tryed many delphi components.
This was the only tool that give me access to this db.
Very fast and very simple
Thanks
Hello Tim, hello guys
I want to come back to my question above from April 9th, because I still didn’t find out how to filter or to retrieve certain records.
Can someone post a short sample for this? Many thanks in advance.
At the moment I always have to retrieve all records and then filter them according their fields. That’s not the best way using large amount of records.
Micha
@Micha
What version of the Sqlite DLL are you using? I need to test it with the latest version – it is waiting for a spare moment!
Tim
Hello Tim
Sorry for my delayed answer.
I used the file from 2008 August 05. Now I use the latest version 3.6.23.1 from 2010 March 29.
It would be VERY great if you could help me with the issue.
Thanks in advance!
Micha
@Micha
try ‘Select * From Mp3Record Where Genre=”Disco”;’
Hi,
I add a dynamic load library version of SQLite3d for C++ Builder,
and made some changes of SQLiteTable3 to support Unicode.
http://kensoft.byethost24.com/Sqlite3wrapper.7z