[yunqa.de] Re: schema error
- From: Delphi Inspiration <delphi@xxxxxxxx>
- To: yunqa@xxxxxxxxxxxxx,<yunqa@xxxxxxxxxxxxx>
- Date: Wed, 08 Jul 2009 18:00:06 +0200
At 15:50 08.07.2009, Radovan Antloga wrote:
>I use my own sqlite tool for exploring databases.
>I did not investigate enough to see where exactly
>problem is. With this tool I often call GetTableNames
>function. So I modified test program to see error.
Use sqlite3_perpare_v2() instead of sqlite3_prepare(). sqlite3_prepare_v2()
will cause sqlite3_step() to reprepare the statement in case of SQLITE_SCHEMA.
Here are the details from the help file:
The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are recommended
for all new programs. The two older interfaces are retained for backwards
compatibility, but their use is discouraged. In the "v2" interfaces, the
prepared statement that is returned (the sqlite3_stmt object) contains a copy
of the original SQL text. This causes the sqlite3_step() interface to behave a
differently in two ways:
1. If the database schema changes, instead of returning SQLITE_SCHEMA as it
always used to do, sqlite3_step() will automatically recompile the SQL
statement and try to run it again. If the schema has changed in a way that
makes the statement no longer valid, sqlite3_step() will still return
SQLITE_SCHEMA. But unlike the legacy behavior, SQLITE_SCHEMA is now a fatal
error. Calling sqlite3_prepare_v2() again will not make the error go away.
Note: use sqlite3_errmsg() to find the text of the parsing error that results
in an SQLITE_SCHEMA return.
2. When an error occurs, sqlite3_step() will return one of the detailed error
codes or extended error codes. The legacy behavior was that sqlite3_step()
would only return a generic SQLITE_ERROR result code and you would have to make
a second call to sqlite3_reset() in order to find the underlying cause of the
problem. With the "v2" prepare interfaces, the underlying reason for the error
is returned immediately.
Ralf
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