Question

I am developing a app for a movie in which I need to fetch data from the database considering some constraints. It works perfectly on the first occasion, but when I try to fetch data 2nd time it throws a runtime exception( the app crashes).I have to bind 3 placeholders. 2 are text and 1 is integer type. Here’s the code which I am using to fetch data from the database.

-(void) Data2
{
 databaseName = @"Cinema1.sqlite";

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

 [self checkAndCreateDatabase];


 sqlite3 *database;
 if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
 {
  if(detailStmt == nil)
  {
   const char *sql = "Select PVR,Fame,Cinemax,Big from listing where UPPER(State) = UPPER(?) and UPPER(City) = UPPER(?) and ZIP = ?";   
   if(sqlite3_prepare_v2(database, sql, -1, &detailStmt, NULL) == SQLITE_OK) 
   {  
    NSLog(@"Hiiiiiii");
    sqlite3_bind_text(detailStmt, 1, [t1 UTF8String], -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(detailStmt, 2, [t2 UTF8String], -2, SQLITE_TRANSIENT);
    sqlite3_bind_int(detailStmt, 3, t3);
    if(SQLITE_DONE != sqlite3_step(detailStmt))
    {
     NSLog(@"Helllloooooo");
     NSString *pvr= [NSString stringWithUTF8String:(char *)sqlite3_column_text(detailStmt, 0)];
     NSString *fame= [NSString stringWithUTF8String:(char *)sqlite3_column_text(detailStmt, 1)];;
     NSString *cinemax = [NSString stringWithUTF8String:(char *)sqlite3_column_text(detailStmt, 2)];
     NSString *big= [NSString stringWithUTF8String:(char *)sqlite3_column_text(detailStmt, 3)];
     pvr1 = pvr;
     fame1 = fame;
     cinemax1 = cinemax;
     big1 = big;
     NSLog(@"PVR %@ Fame %@ Cinemax %@ Big %@",pvr1,fame1,cinemax1,big1);
    }
   }
   sqlite3_finalize(detailStmt);
  }
 }
 sqlite3_close(database);}

Can anyone help me with this.

Answer 1

You are using the sqlite3_prepare_v2() and sqlite3_finalize() wrong. You only prepare a statement once and then you can bind values to it as much as you’d like. When you’re done you call sqlite3_reset(). When you’re completely done with this statement and won’t ever use it again (i.e. you quit the app), then you use finalize.

Your app crashes because you finalize the statement, but the pointer detailStmt still points to the position where your statement once was, and tries to access that region of the memory.

See also here: http://www.sqlite.org/c3ref/prepare.html