有没有更好的方法来更新 sqlite 表？答案

【问题标题】：Is there a better way to update sqlite table?有没有更好的方法来更新 sqlite 表？
【发布时间】：2014-04-14 18:18:51
【问题描述】：

我一直在使用以下代码更新我的 sqlite 表中的数据，但一直认为这不是最佳方式。基本上，因为我不知道我的二维 NSMutableArray 中的数据是什么以及在哪里被用户更新了，所以我正在做的是删除表，用所有列再次创建它，然后在其中插入数据。

通过表和我的数组之间的某种数据比较，有没有更好的方法来做到这一点。请指出您在以下方面看到的任何其他不当行为：

-(void)updateCurrentItemsData:(NSArray *) dataArray
{
NSArray *paths= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory=[paths objectAtIndex:0];
gameDBPath=[documentsDirectory stringByAppendingPathComponent:@"gameData.sqlite"];
const char *dbpath = [gameDBPath UTF8String];
int test;
char *errMsg;
if (sqlite3_open(dbpath, &gamedatabase)==SQLITE_OK)
{
    NSString *querySQL = [NSString stringWithFormat:@"DELETE FROM currentitems"];
    const char *query_stmt = [querySQL UTF8String];
    test=sqlite3_exec(gamedatabase, query_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 1 %i",test);

    const char *sql_stmt = "CREATE TABLE IF NOT EXISTS currentitems(itemid, name, quantity, damaged, price)";
    test=sqlite3_exec(gamedatabase, sql_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 2 %i",test);
for (int i=0; i<dataArray.count; i++)
{
    NSString *querySQL= [NSString stringWithFormat:@"INSERT INTO currentitems(itemid, name, quantity, damaged, price) VALUES('%i','%@','%i','%i','%i')",[[[dataArray objectAtIndex:i] objectAtIndex:0] intValue],[[dataArray objectAtIndex:i] objectAtIndex:1],[[[dataArray objectAtIndex:i] objectAtIndex:2] intValue],[[[dataArray objectAtIndex:i] objectAtIndex:3] intValue],[[[dataArray objectAtIndex:i] objectAtIndex:4] intValue]];
    //NSLog(@"querySQL is %@",querySQL);

    const char *insert_stmt= [querySQL UTF8String];
    test=sqlite3_exec(gamedatabase, insert_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 3 %i",test);
}
    sqlite3_finalize(statementgame);
    sqlite3_close(gamedatabase);
}

}

感谢收看 :)

【问题讨论】：

标签： ios sql objective-c sqlite

【解决方案1】：

您可以使用事务来提高性能 - 只需查看以下稍作修改的代码：

-(void)updateCurrentItemsData:(NSArray *) dataArray
{
NSArray *paths= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory=[paths objectAtIndex:0];
gameDBPath=[documentsDirectory stringByAppendingPathComponent:@"gameData.sqlite"];
const char *dbpath = [gameDBPath UTF8String];
int test;
char *errMsg;
if (sqlite3_open(dbpath, &gamedatabase)==SQLITE_OK)
{
    NSString *querySQL = [NSString stringWithFormat:@"DELETE FROM currentitems"];
    const char *query_stmt = [querySQL UTF8String];
    test=sqlite3_exec(gamedatabase, query_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 1 %i",test);

    const char *sql_stmt = "CREATE TABLE IF NOT EXISTS currentitems(itemid, name, quantity, damaged, price)";
    test=sqlite3_exec(gamedatabase, sql_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 2 %i",test);

sqlite3_exec(gamedatabase, "BEGIN TRANSACTION", NULL, NULL, NULL);

for (int i=0; i<dataArray.count; i++)
{
    NSString *querySQL= [NSString stringWithFormat:@"INSERT INTO currentitems(itemid, name, quantity, damaged, price) VALUES('%i','%@','%i','%i','%i')",[[[dataArray objectAtIndex:i] objectAtIndex:0] intValue],[[dataArray objectAtIndex:i] objectAtIndex:1],[[[dataArray objectAtIndex:i] objectAtIndex:2] intValue],[[[dataArray objectAtIndex:i] objectAtIndex:3] intValue],[[[dataArray objectAtIndex:i] objectAtIndex:4] intValue]];
    //NSLog(@"querySQL is %@",querySQL);

    const char *insert_stmt= [querySQL UTF8String];
    test=sqlite3_exec(gamedatabase, insert_stmt, NULL, NULL, &errMsg);
    if (test!=0) NSLog(@"exec is 5 3 %i",test);
}

sqlite3_exec(gamedatabase, "COMMIT TRANSACTION", NULL, NULL, NULL);

    sqlite3_finalize(statementgame);
    sqlite3_close(gamedatabase);
}

}

【讨论】：