我正在创建一个应用程序，其中数据被传输到包含2个表的数据库，而对于主表，我需要检查我尝试插入的记录是否已经存在。
如果找到记录，则其Id用于与要存储在第二个表中的记录一起存储。
如果在第一个表中找不到记录，则会创建一个新条目，并将新记录的id与第二个表中的数据一起存储
我在每次插入前执行select时遇到问题，如果记录存在，则获取现有ID。
到目前为止，我已经提到了这些链接，但这只是帮助我提高插入速度但是当我使用select时减慢速度 Improve INSERT-per-second performance of SQLite?
我想过使用INSERT OR IGNORE检查记录是否存在，如果没有将它插入数据库，但即使在这种情况下也要获取记录的Id我需要做一个选择
使用代码：
int TransferUrls(int numberOfEntries, PCHAR dbName, PCHAR urlList)
{
sqlite3 *dbHandle = NULL;
int returnCode = 0;
int mainTableEntryNumber = 0;
int processedUrlId = 0;
int returnCode1 = 0;
sqlite3_stmt *selectIdStatement = NULL;
sqlite3_stmt *insertProcessedUrl = NULL;
sqlite3_stmt *insertRawUrl = NULL;
int numberOfEntriesRead = 0;
clock_t cStartClock;
WCHAR rawUrl[MAX_URL_LENGTH] = L"";
CHAR processedUrl[MAX_URL_LENGTH] = "";
CHAR url[MAX_URL_LENGTH] = "";
int status = 0;
FILE *fp = NULL;
errno_t err;
memset(rawUrl, '\0', sizeof(rawUrl));
memset(processedUrl, '\0', sizeof(processedUrl));
memset(url , '\0', sizeof(url));
//open the file from which we are goin to read the links
err = fopen_s(&fp, urlList, "r");
if(err != 0)
{
printf("Error opening the file to transfer urls to databse\n");
return TRANSFER_ERROR;
}
//open a connection to the database in which we would have to enter
returnCode = sqlite3_open(dbName, &dbHandle);
if(returnCode != SQLITE_OK)
{
printf("Error occured while opening database \n");
return TRANSFER_ERROR;
}
//Get the idNo from the MainTable, used for some calculation , ignore it
if(getLastIdNumber(dbHandle, mainTableEntryNumber) == ERROR)
{
fclose(fp);
sqlite3_close(dbHandle);
return TRANSFER_ERROR;
}
//Create a prepared statement to get entry number for an processed url
returnCode = sqlite3_prepare_v2(dbHandle, "SELECT idNo FROM urlDetails where processedUrl = ?;", -1, &selectIdStatement, NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured while preparing select statement for getting idNo\n");
printf("Error msg : %s \n", sqlite3_errmsg(dbHandle));
fclose(fp);
sqlite3_close(dbHandle);
return TRANSFER_ERROR;
}
//create prepared statememnt to insert entry in main table for the processed url
returnCode = sqlite3_prepare_v2(dbHandle, "INSERT INTO urlDetails(idNo, processedUrl, insertTime) VALUES(?, ?, datetime('now','unixepoch', 'localtime'));", -1, &insertProcessedUrl, NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured wile preparing insert statement to insert values for processed url\n");
printf("Error msg: %s\n", sqlite3_errmsg(dbHandle));
sqlite3_finalize(selectIdStatement);
fclose(fp);
sqlite3_close(dbHandle);
return TRANSFER_ERROR;
}
returnCode = sqlite3_prepare_v2(dbHandle, "INSERT INTO urlData VALUES(?, ?);", -1, &insertRawUrl, NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured wile preparing insert statement to insert values for raw url\n");
printf("Error msg: %s\n", sqlite3_errmsg(dbHandle));
sqlite3_finalize(selectIdStatement);
sqlite3_finalize(insertProcessedUrl);
fclose(fp);
sqlite3_close(dbHandle);
return TRANSFER_ERROR;
}
//make synchronous mode off
returnCode = sqlite3_exec(dbHandle, "PRAGMA synchronous = OFF;", NULL, NULL,NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured while making pragma synchronous mode off\n");
status = TRANSFER_ERROR;
goto EXIT;
}
//make journal_mode to memory
returnCode = sqlite3_exec(dbHandle, "PRAGMA journal_mode = OFF;", NULL, NULL,NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured while making pragma jorunal mode to memory\n");
status = TRANSFER_ERROR;
goto EXIT;
}
returnCode = sqlite3_exec(dbHandle,"BEGIN TRANSACTION;", NULL , NULL , NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured while making pragma synchronous mode off\n");
status = TRANSFER_ERROR;
goto EXIT;
}
// get the number of seconds since the program was run
cStartClock = clock();
int entryNumber = 0;
//Read data from a table which consists of raw url and insert the data in both the tables urlData and urlDetails based on conditions
while(fgets(url, MAX_URL_LENGTH, fp) != NULL)
{
entryNumber++;
//check for the number of entries
if(entryNumber == numberOfEntries)
{
break;
}
else
{
memset(rawUrl, '\0', sizeof(rawUrl));
//Replace the trailing newline character in string with string terminating character
size_t len = strlen(url);
if (len > 0 && url[len-1] == '\n')
{
url[--len] = '\0';
}
//printf("Entry %d : %s\n",entryNumber, url);
numberOfEntriesRead++;
//printf("Url is %s \n", url);
//getting the name for the rawUrl
if(swprintf_s(rawUrl, MAX_URL_LENGTH, L"http://%S", url) == -1)
{
printf("Error occured while preparing raw url for %s \n", url);
continue;
}
//here we will perform the further operation i.e give a task to the user i.e get the processed url
if(getUrlDetails(rawUrl, processedUrl) == GET_URL_ERROR)
{
printf("Error occured while gettting processed url from %s raw url\n", rawUrl);
continue;
}
//1. check for the url in the database
//2. If present then store its id number and make an entry for the raw url
//3. if not present then store the id number for the proceesed url ,and make entry for both processed and raw url
returnCode = sqlite3_bind_text(selectIdStatement, 1, processedUrl, -1, NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occcured while binding for select Id statement for url %s\n", processedUrl);
printf("Error msg : %s \n",sqlite3_errmsg(dbHandle));
status = TRANSFER_ERROR;
break;
}
returnCode = sqlite3_step(selectIdStatement);
if(returnCode == SQLITE_ROW)
{
//this indicates that the processed url is already present in the database
processedUrlId = sqlite3_column_int(selectIdStatement, 0);
}
else if (returnCode == SQLITE_DONE)
{
mainTableEntryNumber++;
processedUrlId = mainTableEntryNumber;
//make an entry for the processed url in the table
//bind values to insert statement to set the idNumber
returnCode = sqlite3_bind_int(insertProcessedUrl, 1, processedUrlId);
if(returnCode != SQLITE_OK)
{
printf("Error occured while binding select statement for insert statement \n");
status = TRANSFER_ERROR;
break;
}
//bind the name of the proceesed url to the insert statement for making a new entry in Main table
returnCode = sqlite3_bind_text(insertProcessedUrl, 2, processedUrl, -1, NULL);
if(returnCode != SQLITE_OK)
{
printf("Error occured while binding select statement for insert statement \n");
status = TRANSFER_ERROR;
break;
}
//execute the insert statement
returnCode = sqlite3_step(insertProcessedUrl);
if(returnCode != SQLITE_DONE)
{
printf("Error occured while insert entry into the new table \n");
printf("Error msg: %s\n", sqlite3_errmsg(dbHandle));
status = TRANSFER_ERROR;
break;
}
sqlite3_reset(insertProcessedUrl);
}
else if (returnCode == SQLITE_ERROR)
{
printf("Error occured while fetching data for processed url %s\n", processedUrl);
status = TRANSFER_ERROR;
break;
}
//make an entry for the raw url into the other table
sqlite3_bind_text(insertRawUrl, 1, url,-1, NULL);
sqlite3_bind_int(insertRawUrl, 2, processedUrlId);
returnCode = sqlite3_step(insertRawUrl);
if(returnCode != SQLITE_DONE)
{
printf("Error occured while inserting an entry for the raw url \n");
printf("Error msg : %s\n", sqlite3_errmsg(dbHandle));
status = TRANSFER_ERROR;
break;
}
sqlite3_reset(insertRawUrl);
sqlite3_reset(selectIdStatement);
}
memset(url, '\0', sizeof(url));
}
//Calculate the number of seconds required for the program to complete
printf("%d Entries were processed in %4.6f seconds\n", numberOfEntriesRead, (clock() - cStartClock)/(double)CLOCKS_PER_SEC);
sqlite3_exec(dbHandle,"END TRANSACTION;", NULL , NULL , NULL);
//free the memory allocated for the select statement as we are done with it
EXIT : sqlite3_finalize(selectIdStatement);
sqlite3_finalize(insertProcessedUrl);
sqlite3_finalize(insertRawUrl);
//Close the handle to the database connection
sqlite3_close(dbHandle);
//close the handle to file
fclose(fp);
return status;
}