Unable to remove data from database ios - iphone

Question

I have database, but when i tried to remove data from the database nothing happens, what should i do to make sure it works? Because when i pressed delete the dta is still in the database
This is the code:
/file path to database
-(NSString*)filePath {
NSArray*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
return [[paths objectAtIndex:0]stringByAppendingPathComponent:#"bp.sql"];
}
//open database
-(void)openDB {
if(sqlite3_open([[self filePath]UTF8String], &db) !=SQLITE_OK) {
sqlite3_close(db);
NSAssert(0, #"Databese failed to open");
}
else {
NSLog(#"database opemed");
}
}
- (IBAction)del:(id)sender {
NSString*sql = [NSString stringWithFormat:#"DELETE key, theDate, customer, code1, code2 FROM summary WHERE key=\"%#\"",customerName];
const char* query_stmt = [sql UTF8String];
sqlite3_stmt*statement;
sqlite3_prepare_v2(db, query_stmt, -1, & statement, NULL);
if (sqlite3_step(statement) == SQLITE_DONE)
{
NSAssert(0, #"database object delete failed");
} else {
NSLog(#"No error");
}
sqlite3_finalize(statement);
sqlite3_close(db)

Answer 1

You can't delete specific column values using the DELETE query. It's for removing the entire row.
The problem is with the following query:
NSString*sql = [NSString stringWithFormat:#"DELETE key, theDate, customer, code1, code2 FROM summary WHERE key=\"%#\"",customerName];
Change it to:
NSString*sql = [NSString stringWithFormat:#"DELETE FROM summary WHERE key=\"%#\"",customerName];
If you need to remove particular column value of a row use the UPDATE query.
Please check the sqlite documentation for the details

Answer 2

All the functions that you wrote like checking filepath, opendb should occur in the same function(maybe inside your del function).
This is how I will do it:
-(void)updateStatus:(NSString *)queryString {
NSString *docsDir;
NSArray *dirPaths;
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
strDatabasePath = [NSString stringWithString:[docsDir stringByAppendingPathComponent:#"bp.sql"]];
NSFileManager *filemgr = [NSFileManager defaultManager];
if ([filemgr fileExistsAtPath: strDatabasePath] == YES)
{
const char *dbpath = [strDatabasePath UTF8String];
if (sqlite3_open(dbpath, &sqlDatabase) == SQLITE_OK)
{
const char* beginString = "BEGIN;";
sqlite3_stmt *compiledstatement;
sqlite3_prepare_v2(sqlDatabase, beginString, -1, &compiledstatement, NULL);
if (sqlite3_step(compiledstatement) == SQLITE_DONE) {}
else DLog(#"Failed!");
sqlite3_finalize(compiledstatement);
DLog(#"QUERY : %#",queryString);
const char *selectStatement = [queryString UTF8String];
sqlite3_prepare_v2(sqlDatabase, selectStatement, -1, &compiledstatement, NULL);
//sqlite3_bind_text(compiledstatement,1,[statusString UTF8String],-1,SQLITE_TRANSIENT);
if (sqlite3_step(compiledstatement) == SQLITE_DONE) {}
else DLog(#"Failed!");
sqlite3_finalize(compiledstatement);
const char* endString="END;";
sqlite3_prepare_v2(sqlDatabase, endString, -1, &compiledstatement, NULL);
if (sqlite3_step(compiledstatement) == SQLITE_DONE) {}
else DLog(#"Failed!");
sqlite3_finalize(compiledstatement);
sqlite3_close(sqlDatabase);
}
else DLog(#"Failed to open table");
}
}
NSString *queryString;
queryString = [NSString stringWithFormat:#"DELETE key, theDate, customer, code1, code2 FROM summary WHERE key=\"%#\"",customerName];
[self updateStatus:queryString];
Hope this helps...

Answer 3

-(BOOL)DeleteWishList:(int)rowno
{
NSString *queryString=[NSString stringWithFormat:#"delete from wishtable where _id=%d",rowno];
[self openDB];
char *err;
if (sqlite3_exec(dBObject, [queryString UTF8String], NULL,NULL, &err)!= SQLITE_OK)
{
sqlite3_close(dBObject);
return NO;
}
else
{
return YES;
}
}