參考代碼

• 第一段
• 這個親測可以使用

#include <sqlite3.h> #include <iostream> /* ** Perform an online backup of database pDb to the database file named ** by zFilename. This function copies 5 database pages from pDb to ** zFilename, then unlocks pDb and sleeps for 250 ms, then repeats the ** process until the entire database is backed up. ** ** The third argument passed to this function must be a pointer to a progress ** function. After each set of 5 pages is backed up, the progress function ** is invoked with two integer parameters: the number of pages left to ** copy, and the total number of pages in the source file. This information ** may be used, for example, to update a GUI progress bar. ** ** While this function is running, another thread may use the database pDb, or ** another process may access the underlying database file via a separate ** connection. ** ** If the backup process is successfully completed, SQLITE_OK is returned. ** Otherwise, if an error occurs, an SQLite error code is returned. ** 官網地址：https://sqlite.org/backup.html */int backupDb(sqlite3 *pDb, /* Database to back up */const char *zFilename /* Name of file to back up to */ // void(*xProgress)(int, int) /* Progress function to invoke */ ){int rc; /* Function return code */sqlite3 *pFile; /* Database connection opened on zFilename */sqlite3_backup *pBackup; /* Backup handle used to copy data *//* Open the database file identified by zFilename. */rc = sqlite3_open(zFilename, &pFile);if( rc==SQLITE_OK ){/* Open the sqlite3_backup object used to accomplish the transfer */pBackup = sqlite3_backup_init(pFile, "main", pDb, "main");if( pBackup ){/* Each iteration of this loop copies 5 database pages from database** pDb to the backup database. If the return value of backup_step()** indicates that there are still further pages to copy, sleep for** 250 ms before repeating. */do {rc = sqlite3_backup_step(pBackup, 5); // xProgress(sqlite3_backup_remaining(pBackup);sqlite3_backup_pagecount(pBackup); // );if( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED ){sqlite3_sleep(250);}} while( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED );/* Release resources allocated by backup_init(). */(void)sqlite3_backup_finish(pBackup);}rc = sqlite3_errcode(pFile);}/* Close the database connection opened on database file zFilename** and return the result of this function. */(void)sqlite3_close(pFile);return rc; }

• 第二段
• 這個使用不順利，不知道是不是打開的方式不對

#pragma once#include <sqlite3.h> namespace hsm { namespace common {/*** @brief 備份和恢復數據庫數據* @param pInMemory 指向內存數據庫的指針* @param zFilename 指向文件數據庫目錄的字符串指針* @param isSave 0：從文件數據庫恢復到內存數據庫* 1：從內存數據庫備份到文件數據庫* @return 狀態碼*/ int backup_or_restore(sqlite3 *pInMemory,const char* zFilename,int isSave){int rc;sqlite3 *pFile;sqlite3_backup *pBackup;sqlite3 *pTo;sqlite3 *pFrom;rc = sqlite3_open(zFilename,&pFile);if (rc == SQLITE_OK){pFrom = (isSave?pInMemory:pFile);pTo = (isSave?pFile:pInMemory);pBackup = sqlite3_backup_init(pTo,"main",pFrom,"main");if (pBackup){(void)sqlite3_backup_step(pBackup,-1);(void)sqlite3_backup_finish(pBackup);}rc = sqlite3_close(pFile);}return rc; } } // namespace common } // namespace hsm

對于backup函數的調用例子

void KeyStorage::backup(const std::string &filename) {sqlite3 *pDB;int rc = sqlite3_open(MGMT_KEY_STORAGE_FILE, &pDB);if( rc==SQLITE_OK ){printf("open test.db OK!\n");rc = backupDb(pDB, MGMT_KEY_STORAGE_FILE);if( rc==SQLITE_OK ){printf("backupDb new.db OK!\n");} else {printf("backupDb new.db error!\n");}} else {printf("open test.db error!\n");} }

參考鏈接

• https://sqlite.org/backup.html

總結

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