Daten aus der Datenbank in ios können nicht abgerufen werden
-
27-10-2019 - |
Frage
Ich möchte einige Daten in einer SQLite-Datenbank speichern und lesen. Es gibt kein Problem beim Speichern der Daten, aber ich kann keine Daten aus der Datenbank abrufen.
Hier ist der Code, den ich verwende.
//>>>>>> 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);
}
}
Bitte geben Sie die Lösung an.
Vielen Dank im Voraus
Lösung
Erstellen Sie die Datenbank zur Laufzeit und verwenden Sie die folgende Logik:
, um die Daten in SQLite zu schreiben.
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);
Zum Lesen von Daten aus SQLite
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);
Probieren Sie dies aus und stimmen Sie mich ab, wenn es für Sie gut funktioniert.
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