充分利用SQLite的INT值 [英] Getting int values from SQLite

问题描述

我听说使用 sqlite3_ prepare_v2 而不是 sqlite_exec 来从数据库中获得的整数，但我失败了找到任何的例子。 这页面是无益也。现在我正在从数据库的字符串，所以我需要用来分析它们的atoi 这似乎是缓慢和无效的。
有很多关于这样类似的问题，但他们对OBJ-C和iOS SDK。我需要C / C ++提示或例子。
先谢谢了。

I heard of using sqlite3_prepare_v2 instead of sqlite_exec to get integers from database, but I failed to find any examples. This page wasn't helpful also. Now I am getting strings from database, so I need to parse them with atoi and this seems to be slow and ineffective. There a lot of similar questions on SO, but they are about obj-c and iOS SDK. I need C/C++ hint or example. Thanks in advance.

推荐答案

在 sqlite3_ prepare 成功，你一定不要忘记清理语句 sqlite3_finalize 。
为了得到结果记录，通话 sqlite3_step ，直到它不会返回 SQLITE_ROW 。
为了得到当前结果记录的值，调用 sqlite3_column_ *功能的：

After sqlite3_prepare has succeeded, you must not forget to clean up the statement with sqlite3_finalize. To get the result records, call sqlite3_step until it does not return SQLITE_ROW. To get the values of the current result record, call the sqlite3_column_* functions:

sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(db, "SELECT 42", -1, &stmt, NULL) != SQLITE_OK)
    ...error...
else {
    for (;;) {
        int rc = sqlite3_step(stmt);
        if (rc == SQLITE_DONE)
            break;
        if (rc != SQLITE_ROW) {
            ...error...
            break;
        }
        printf("value: %d\n", sqlite3_column_int(stmt, 0));
    }
    sqlite3_finalize(stmt);
}

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