无法从ios中的数据库中检索数据

Question

我想将一些数据保存到sqlite数据库并读取它，保存数据时没有问题，但我无法从数据库检索数据。

这是我正在使用的代码。

//>>>>>> to save in sqlite Database 

-(void)saveData 
{ 
    NSString *strTxtFldValue = txtFldName.text; 

    sqlite3_stmt *statement; 
    const char *dbpath = [appDel.databasePath UTF8String]; 

    if (sqlite3_open(dbpath, &database) == SQLITE_OK) 
    { 
     NSString *insertSQL = [NSString stringWithFormat:@"INSERT INTO TESTTABLE (NAME) VALUES (\"%@\")",strTxtFldValue]; 

     const char *insert_stmt = [insertSQL UTF8String]; 
     sqlite3_prepare_v2(database, insert_stmt, 
          -1, &statement, NULL); 
     if (sqlite3_step(statement) == SQLITE_DONE) 
     { 
      NSLog(@"Data is added succesfully "); 

      UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Confirmation" message:@"Name is added successfully." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
      [alert show]; 
      [alert release]; 
     } else { 

      NSLog(@"Failed to add data"); 
     } 
     sqlite3_finalize(statement); 
     sqlite3_close(database); 
    } 
} 

//>>>>>> to read from database 

//here the control comes till second NSLog and the "sqlite3_prepare_v2" statement doesn't get execute. 

-(void)readData{ 

    const char *dbpath = [appDel.databasePath UTF8String]; 
    sqlite3_stmt *statement; 
    NSLog(@"^^^^^^^ 1"); 

    if (sqlite3_open(dbpath, &database) == SQLITE_OK) 
    { 
     NSLog(@"^^^^^^^ 2"); 

     // NSString *querySQL = [NSString stringWithFormat:@"SELECT * FROM TESTTABLE"]; 
     NSString *querySQL = [NSString stringWithFormat:@"SELECT NAME FROM TESTTABLE"]; 

    const char *query_stmt = [querySQL UTF8String]; 

     **if (sqlite3_prepare_v2(database,query_stmt, -1, &statement, NULL) == SQLITE_OK)** 
     {  
      NSLog(@"^^^^^^^ 3");    
      while(sqlite3_step(statement) == SQLITE_ROW) 
      { 
     NSLog(@"^^^^^^^ 4"); 

     NSString *cName = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 0)]; 
       NSLog(@"~~~~### cName = %@",cName); 

       Names *name = [[Names alloc] initWithName:cName]; 
       [names addObject:name]; 
       [name release];    
      } 

      sqlite3_finalize(statement); 
     } 
     sqlite3_close(database); 
    } 
} 

请提供解决方案。

预先感谢

Answer 1

在运行时创建数据库，并使用下面的逻辑，

在源码写入数据。

sqlite3 *pDb; 
char *databaseName; 

databaseName = @"TempDatabase.sql"; 

NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *documentsDir = [documentPaths objectAtIndex:0]; 
//databasePath = [documentsDir stringByAppendingPathComponent:databaseName]; 

databasePath =[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"TempDatabase.sql"]; 

//[self copyDatabaseIfNeeded]; 


if(sqlite3_open([databasePath UTF8String], &pDb) == SQLITE_OK) 
{ 

    const char *sqlStatement = "INSERT INTO tablename (name) VALUES(?)"; 

    sqlite3_stmt *compiledStatement; 
    if(sqlite3_prepare_v2(pDb, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) 
    { 


     sqlite3_bind_text(compiledStatement, 1, [strTxtFldValue UTF8String], -1, SQLITE_TRANSIENT); 
    } 
    if(sqlite3_step(compiledStatement) != SQLITE_DONE) 
    { 
     NSLog(@"~~~~~~~~~~~ 1 Error: %s", sqlite3_errmsg(pDb)); 
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Name name is not added." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
     [alert show]; 
     [alert release]; 

    } else { 

     UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Confirmation" message:@"name is added successfully." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
     [alert show]; 
     [alert release]; 

      } 
    sqlite3_finalize(compiledStatement); 
} 

sqlite3_close(pDb); 

要读取从源码

数据

 sqlite3 *database; 
const char *dbpath = [appDel.databasePath UTF8String]; 
sqlite3_stmt *statement; 


NSMutableArray *names = [[NSMutableArray alloc]init]; 

if (sqlite3_open(dbpath, &database) == SQLITE_OK) 
{ 


    const char *sqlStatement = "select name from tablename"; 


    if (sqlite3_prepare_v2(database, sqlStatement, -1, &statement, NULL) == SQLITE_OK) { 
     while (sqlite3_step(statement) == SQLITE_ROW) 
     { 
      NSString *cName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,0)]; 
      //NSLog(@"cName = %@",cName); 

      Names *name = [[Names alloc] initWithName:cName]; 
      [names addObject:name]; 
      [name release]; 
     } 

    } 
    sqlite3_finalize(statement); 

} 
sqlite3_close(database); 

尝试了这一点，并投我，如果它工作正常，为您服务。