SQLite - How to use prepared statements? - sql

Question

I am trying out Tim Anderson's SQLite3 Wrapper for Delphi and I am currently having problems using Prepared Statements. I can't use the extended variant by SV since I need to stay compatible with Delphi 6.
This is what I have tried so far:
var
sldb: TSQLiteDatabase;
sltb: TSQLIteTable;
q: TSQLiteQuery;
begin
sldb := TSQLiteDatabase.Create(ADBFile);
if not sldb.TableExists('vmd_nodes') then
begin
sldb.execsql('CREATE TABLE vmd_nodes (content_date BLOB, node_type_oid OID, content_type_pod OID, update_ts TIMESTAMP, create_ts TIMESTAMP, node_guid GUID PRIMARY KEY, parent_guid GUID);');
end;
// Try #1: hardcoded (works)
sltb := slDb.GetTable('SELECT * FROM vmd_nodes WHERE node_guid = "asd"');
try
showmessage(inttostr(sltb.Count)); // Output: 1
finally
sltb.Free;
end;
// Try #2 (does not work)
sltb := slDb.GetTable('SELECT * FROM vmd_nodes WHERE node_guid = ?', ['asd']); // ???
try
showmessage(inttostr(sltb.Count)); // Output: 0
finally
sltb.Free;
end;
// Try #3
sldb.AddParamText('guid', 'asd'); // why is AddParamText member of sldb instead of q ???
q := sldb.PrepareSQL('SELECT * FROM vmd_nodes WHERE node_guid = :guid');
sldb.AddParamText('guid', 'asd'); // why is AddParamText member of sldb instead of q ???
ShowMessage(q.SQL); // SELECT * FROM vmd_nodes WHERE node_guid = :guid => Nothing was replaced
sltb := q; // How to get a TSQLIteTable out of the TSQLiteQuery ?
end;

Answer 1

According to the (somewhat strangely expressed) docs, you first add the parameters, then use GetTable with your SQL to get the results, something like;
sldb.AddParamText(':guid', 'asd');
sltb := sldb.GetTable('SELECT * FROM vmd_nodes WHERE node_guid = :guid');