Function duckdb_value_string_internal 

pub unsafe extern "C" fn duckdb_value_string_internal(
    result: *mut duckdb_result,
    col: idx_t,
    row: idx_t,
) -> duckdb_string

DEPRECATION NOTICE**: This method is scheduled for removal in a future release.

@return The char* value at the specified location. ONLY works on VARCHAR columns and does not auto-cast. If the column is NOT a VARCHAR column this function will return NULL.

The result must NOT be freed.