iphone - iPhone 上 INSERT 的 SQLite 行为

Question

作为我的 iPhone 应用程序的一部分，我目前正在执行以下操作

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"cities.sqlite"];

sqlite3 *database;

if(sqlite3_open([filePath UTF8String], &database) == SQLITE_OK) {
   const char *sqlStatement = "insert into table (name, description, image) VALUES (?, ?, ?)";
   sqlite3_stmt *compiledStatement;
   if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK)    {
      sqlite3_bind_text( compiledStatement, 1, [name UTF8String], -1, SQLITE_TRANSIENT);
      sqlite3_bind_text( compiledStatement, 2, [description UTF8String], -1, SQLITE_TRANSIENT);
      NSData *dataForImage = UIImagePNGRepresentation(image);
      sqlite3_bind_blob( compiledStatement, 3, [dataForImage bytes], [dataForImage length], SQLITE_TRANSIENT);

   }
   if(sqlite3_step(compiledStatement) != SQLITE_DONE ) {
      NSLog( @"Error: %s", sqlite3_errmsg(database) );
   } else {
      NSLog( @"Insert into row id = %d", sqlite3_last_insert_rowid(database));
   }
   sqlite3_finalize(compiledStatement);
}
sqlite3_close(database);

让我感到困惑的是，如果我取出该部分，

   if(sqlite3_step(compiledStatement) != SQLITE_DONE ) {
      NSLog( @"Error: %s", sqlite3_errmsg(database) );
   } else {
      NSLog( @"Insert into row id = %d", sqlite3_last_insert_rowid(database));
   }

INSERT 未保存到数据库并丢失。我假设我在这里遗漏了一些明显的东西？

Answer 1

当然不会被插入。您需要调用 sqlite3_step 才能真正执行您的语句。

检查 the documentation出。

这是 SQLITE 的东西，不是 iPhone 特定的东西。

来自文档:

After a prepared statement has been prepared using either sqlite3_prepare_v2() or sqlite3_prepare16_v2() or one of the legacy interfaces sqlite3_prepare() or sqlite3_prepare16(), this function must be called one or more times to evaluate the statement.