Question

我有一个循环通过SQLite3数据库的C ++应用程序。每行包含一个ID，该ID根据向量进行检查。如果向量中不存在DB中的ID，则应使用预准备语句删除它。我使用以下代码，但ID不会被删除。我也无法从sqlite3_step(stmt2)函数中收到错误消息。

//SETTINGS["Reference"] CONTAINS THE REFERENCE FOR THE ID's (IT's 1 FOR UNDERNEATH EXAMPLE)


vector<int> IDs; //THIS VECTOR CONTAINS THE ID's IN MY APPLICATION
rc = sqlite3_prepare_v2(db, "SELECT ID FROM Files WHERE Reference=?", -1, &stmt, 0);
sqlite3_bind_text(stmt, 1, Settings["Reference"].c_str(), Settings["Reference"].length(), 0);
CheckDBError(rc);
rc = sqlite3_step(stmt);
sqlite3_stmt* stmt2;
int rc2 = sqlite3_prepare_v2(db, "DELETE FROM Files WHERE ID=? AND Reference=?", -1, &stmt2, 0);
CheckDBError(rc2);
while(rc == SQLITE_ROW) {
    string IDToCheck = NumberToString(sqlite3_column_int64(stmt, 0));
    if (std::find(IDs.begin(), IDs.end(), IDToCheck) == IDs.end()) { //VERIFY AGAINST VECTOR WORKS AS EXPECTED

        //I GET HERE WITH ALL MY ID's I HAVE CHECKED THAT ALREADY :)

        sqlite3_bind_text(stmt2, 1, IDToCheck.c_str(), IDToCheck.length(), 0);
        sqlite3_bind_text(stmt2, 2, Settings["Reference"].c_str(), Settings["Reference"].length(), 0);
        rc2 = sqlite3_step(stmt2);

        //CAN'T GET ANY ERROR MESSAGE (SO QUERY IS FINE, WHICH SEEMS LIKE IT?)

        }
    rc = sqlite3_step(stmt);
    }
sqlite3_finalize(stmt);
sqlite3_finalize(stmt2);

Answer 1

你不能在finalize块之前调用while函数，因为这样你在使用它之前就完成了你的陈述。根据{{3}}（强调我的）：

尝试使用已准备好的应用程序是一个严重错误完成后的声明。任何使用准备好的声明在最终确定之后会导致未定义且不合需要行为，例如段错误和堆损坏。

C ++ SQLite3编写的delete语句无法正常工作

1 个答案: