[yunqa.de] Re: SQLite metadata
- From: "Radovan Antloga" <radovan.antloga@xxxxxxxx>
- To: <yunqa@xxxxxxxxxxxxx>
- Date: Fri, 5 Jun 2009 09:08:00 +0200
Thank you! I renamed and included prepare function for UTF16.
I would like to ask you about a feature request in sqlite I have.
I have similar query object inspired by your uniquery but field
maping supports types: [WIDE]TEXT, [WIDE][VAR]CHAR,
INTEGER, SMALLINT, LARGEINT | BIGINT, REAL, FLOAT,
NUMERIC, DECIMAL, CURRENCY, DATE, TIME, DATETIME,
TIMESTAMP, BOOLEAN, BLOB, ZBLOB (ZLib compressed).
For expression fields (count(*), avg(), sum()) I have added
ability to read type from field alias (count(*) "CNT:integer")
so I could map field in query. If I forget alias, I map fields with
no affinity to variants. I wonder to ask drh if he can improve
sqlite to return affinity (not just NONE) for expression fields.
Best Regards,
R.Antloga
----- Original Message -----
From: "Delphi Inspiration" <delphi@xxxxxxxx>
To: <yunqa@xxxxxxxxxxxxx>
Sent: 4. junij 2009 18:23
Subject: [yunqa.de] Re: SQLite metadata
At 09:45 04.06.2009, Radovan Antloga wrote:
You would probably add this to DISQLite3 to in next release.
I have done it already so I created new function:
function sqlite3_prepare(Db: sqlite3; const zSQL: PAnsiChar; nByte:
integer;
ppStmt: sqlite3_stmt_ptr; const pzTail: PPUtf8Char): Integer;
var
Retries: integer;
begin
Retries := 0;
repeat
Inc(Retries);
Result := sqlite3_prepare_v2(DB, zSQL, nByte, ppStmt, pzTail);
until (Retries > 1) or (Result <> SQLITE_SCHEMA);
end;
and replaced all sqlite3_prepare_v2 with new sqlite3_prepare.
Yes, but I can not redefine sqlite3_prepare (and similar functions)
because this would break the original SQLite API.
Instead, I will add two new functions (see below) to DISQLite3Api.pas and
call them throughout the DISQLite3 library wherever appropriate. They wrap
around the recommended sqlite3_prepare_v2(). As the name suggests, they
should be seen as "internal" functions only which could change without
notice.
Ralf
//------------------------------------------------------------------------------
function sqlite3_prepare_internal(
DB: sqlite3; // Database handle.
const zSql: PUtf8Char; // SQL statement, UTF-8 encoded.
nByte: Integer; // Maximum length of zSql in bytes.
ppStmt: sqlite3_stmt_ptr; // OUT: Statement handle.
const pzTail: PPUtf8Char // OUT: Pointer to unused portion of zSql.
): Integer;
var
Retries: Cardinal;
begin
Retries := 0;
repeat
Inc(Retries);
Result := sqlite3_prepare_v2(DB, zSql, nByte, ppStmt, pzTail);
until (Result <> SQLITE_SCHEMA) or (Retries > 1);
end;
//------------------------------------------------------------------------------
{$IFNDEF SQLITE_OMIT_UTF16}
function sqlite3_prepare16_internal(
DB: sqlite3; // Database handle.
const zSql: PWideChar; // SQL statement, UTF-16 encoded.
nByte: Integer; // Maximum length of zSql in bytes.
ppStmt: sqlite3_stmt_ptr; // OUT: Statement handle.
const pzTail: PPWideChar // OUT: Pointer to unused portion of zSql.
): Integer;
var
Retries: Cardinal;
begin
Retries := 0;
repeat
Inc(Retries);
Result := sqlite3_prepare16_v2(DB, zSql, nByte, ppStmt, pzTail);
until (Result <> SQLITE_SCHEMA) or (Retries > 1);
end;
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