Re: PQexecPrepared() question

Hi, David,

On Thu, Dec 18, 2025 at 7:41 AM David G. Johnston
<david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>
> On Thu, Dec 18, 2025 at 8:20 AM Igor Korot <ikorot01(at)gmail(dot)com> wrote:
>>
>> Imagine following scenario:
>>
>> I have 2 machines. One is running PG server on *nix. Second is my app on Windows.
>>
>> An application starts for the first time.
>>
>> What is “clientencoding in this case?
>
>
> This day in age, probably UTF-8; which is what most servers are initialized using. If you aren't having issues with encoding I suggest you just take for granted that the defaults work in 99% of the cases. If you are having issues, share the details.

My code:

for( int i = 0; i < PQntuples( res ); i++ )
{
std::wstring cat = m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 0 ) );
std::wstring schema = m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 1 ) );
std::wstring table = m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 2 ) );
char *table_owner = PQgetvalue( res, i, 3 );
pimpl.m_tableDefinitions[cat].push_back( TableDefinition(
cat, schema, table ) );
count++;
paramValues = schema + L"." + table;
params[0] = new char[paramValues.length() + 2];
memset( params[0], '\0', paramValues.length() + 2 );
std::wcstombs( params[0], paramValues.c_str(),
paramValues.length() );
params[1] = new char[table.length() + 2];
memset( params[1], '\0', table.length() + 2 );
std::wcstombs( params[1], table.c_str(), table.length() );
params[2] = new char[schema.length() + 2];
memset( params[2], '\0', schema.length() + 2 );
std::wcstombs( params[2], schema.c_str(), schema.length() + 2 );
paramFormat[0] = paramFormat[1] = paramFormat[2] = 0;
paramLength[0] = paramValues.length();
paramLength[1] = table.length();
paramLength[2] = schema.length();
res8 = PQexecPrepared( m_db, "set_table_prop", 3, params,
paramLength, paramFormat, 0 );
if( PQresultStatus( res8 ) != PGRES_COMMAND_OK )
{
std::wstring err = m_pimpl->m_myconv.from_bytes(
PQerrorMessage( m_db ) );
errorMsg.push_back( L"Error executing query: " + err );
result = 1;
}
PQclear( res8 );
delete[] params[0];
params[0] = nullptr;
delete[] params[1];
params[1] = nullptr;
delete[] params[2];
params[2] = nullptr;
}

And ths s what I have n the DB:

table_catalog | table_schema | table_name | table_type |
self_referencing_column_name | reference_generation |
user_defined_type_catalog | user_defined_type_schema |
user_defined_type_name | is_insertable_into | is_typed | commit_action
---------------+--------------+------------+------------+------------------------------+----------------------+---------------------------+--------------------------+-
-----------------------+--------------------+----------+---------------
draft | public | abcß | BASE TABLE |
| | |
|
| YES | NO |

Using my setup above and assumng my Win locale is en_US.UTF8 I can
successfullly retreve
that record but the insertion fails with

Invalid byte sequence for parameter $1 in UTF8

Thank you.

>
> David J.
>