获取的行数从SQLite的C接口在Objective-C [英] Getting number of rows from SQLite C interface in Objective-C

问题描述

我是新来的Objective-C和iPhone应用程序。

I am new to objective-C and iphone apps.

我访问SQLite和在我的表咖啡的3行。我用下面的方法来从表抢了某事，但是，只有第二和第三行被拉出{第一行始终无缘}。是，由于通过检查而sqlite3_step（selectstmt）返回SQLITE_ROW是错误的，我while循环逻辑？这里是code：

I am accessing SQLite and have 3 rows in my table "coffee". I used the following way to grab sth out from the table, however, only then 2nd and 3rd rows are being pulled out {the 1st row is always missed}. Is that due to the logic in my while loop by checking while sqlite3_step(selectstmt) returns SQLITE_ROW is wrong? Here is the code:

if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {

  const char *sql = "select coffeeID, coffeeName from coffee";
  sqlite3_stmt *selectstmt;
  NSLog(@"sqlite_prepare_v2 returns: %i", sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL));

  if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {

   NSLog(@"sqlite3_step returns: %i", sqlite3_step(selectstmt));
   while(sqlite3_step(selectstmt) == SQLITE_ROW) {

    NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
    Coffee *coffeeObj = [[Coffee alloc] initWithPrimaryKey:primaryKey];
    coffeeObj.coffeeName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];
    NSLog(@"this is the coffee name: %@", coffeeObj.coffeeName);
    coffeeObj.isDirty = NO;

    [appDelegate.coffeeArray addObject:coffeeObj];
    [coffeeObj release];
   }
  }
 }

在另一方面，是有我直接从SQLite的的C接口检查在查询行returen数任何方便的方式？

On the other hand, is there any convenient way for me to check the number of rows returen in a query directly from the C interface of SQLite?

非常感谢。

推荐答案

您可以使用来自咖啡查询 SELECT COUNT（*）来告诉你有多少行有

You could use the query SELECT COUNT(*) FROM coffee to tell you how many rows there are.

和也，保存自己有些头痛和使用一个SQLite包装。

And also, save yourself some headaches and use a SQLite wrapper.

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