sqlite transaction事务操作

发布时间：2020-12-12 20:30:12 所属栏目：百科来源：网络整理

导读：Start a transaction with: sqlite3_exec(db,"BEGIN",0); Commit a transaction with: 一下的代码是用transaction的，首先尝试了把两个sql语句链接在一起的，用一个sqlite3_prepare——似乎没成功，分开来写，也没成功，难道是有什么特别的？ //sqlite3_exec

Start a transaction with:sqlite3_exec(db,"BEGIN",0);

Commit a transaction with:

 
 一下的代码是用transaction的，首先尝试了把两个sql语句链接在一起的，用一个sqlite3_prepare——似乎没成功，分开来写，也没成功，难道是有什么特别的？ 
  
//sqlite3_exec(database,0); 
    NSLog(@"querySql :%@",sql1); 
    NSLog(@"querySql :%@",sql2); 
 
  
 
  
    if(sqlite3_prepare_v2(database,[sql1 UTF8String],-1,&compiledStatement,NULL) == SQLITE_OK && sqlite3_prepare_v2(database,[sql2 UTF8String],NULL) == SQLITE_OK) 
    { 
     //sqlite3_exec(database,0); 
      retValue=YES; 
    } 
    else { 
     //sqlite3_exec(database,"ROLLBACK",0); 
       
    } 
    sqlite3_finalize(compiledStatement); 
    sqlite3_close(database); 

 
 后来我还是想了好多方法，至少sql语句看起来是可以的，在sql analzer里面是ok的， 
  
if (sqlite3_exec (database,[updateSqlUTF8String],NULL,&errorMsg) != SQLITE_OK) 
{ 
NSLog(@"upate error"); 
       sqlite3_close(database); 
       return NO; 
} 
 
 
 
 
 
 
 
 
 
  
  sqlite3_prepare_v2 
 
 
 

  后来又发现人们评价说“ 
  
  
  BEGIN is a deferred operation. Deferred means that no locks are acquired on the database until the database is first accessed. Thus with a deferred transaction,the BEGIN statement itself does nothing to the filesystem. Locks are not acquired until the first read or write operation. Seesqlite.org/lang_transaction.htmlfor other variations on BEGIN that do attempt to obtain locks 
  ” 
 老实说没看懂，大概是不建议用这个begin：：： 
 
  
 后来我又看到这么段代码，觉得挺靠谱的： 
  

  //执行事务 
 

  @try { 
 
 
 
   sqlite3_exec(database,"BEGIN TRANSACTION",0); //事务开始 
  
  
  NSString *s = [[NSString alloc] initWithUTF8String:[要执行的sql 语句 UTF8String]]; 
  
  
  char *sql = (char *) [s UTF8String]; 
  
  
  int r = sqlite3_exec( database,sql,0 ); 
  
  
  if(r != SQLITE_OK){ 
  
  
  //NSLog(@" sql: %@",s); 
  
  
  //NSLog(@"r = %d",r); 
  
  
  } 
  
  
  NSLog(@"updateSql %@",ssql); 
  
  
  NSLog(@"r = %d",r); 
  
  
  [s release]; 
  
  
  } 
  
  
  @catch (NSException * em) { 
  
  
  NSLog(@"failed to read %@",[em description]); 
  
  
  } 
  
  
  @finally { 
  
  
  //NSLog(@"failed to read %@",[e description]); 
  
  
  } 
  
  
  
 
  
  
  } 
  
  
  intresult = sqlite3_exec(database,&error); //COMMIT 
  
  
   
  
    我觉得这次应该i哦y验 饿 
   
  
    我把其中一个update搞失败？ 找不到key？ 
   
   
   【2】创建表格 
   //创建表格，假设有五个字段，（id，cid，title，imageData ，imageLen ） 
   //说明一下，id为表格的主键，必须有。 
   //cid，和title都是字符串，imageData是二进制数据，imageLen 是该二进制数据的长度。 - (BOOL) createChannelsTable:(sqlite3*)db{  char *sql = "CREATE TABLE channels (id integer primary key,  cid text,  title text,  imageData BLOB,  imageLen integer)";  sqlite3_stmt *statement;  if(sqlite3_prepare_v2(db,&statement,nil) != SQLITE_OK) {  NSLog(@"Error: failed to prepare statement:create channels table");  return NO;  }  int success = sqlite3_step(statement);  sqlite3_finalize(statement);  if ( success != SQLITE_DONE) {  NSLog(@"Error: failed to dehydrate:CREATE TABLE channels");  return NO;  }  NSLog(@"Create table 'channels' successed.");  return YES; }
                        （编辑：李大同）
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