如何在iPhone项目中通过objecc方法修改sqlite数据库中的表

Question

每一个

我需要添加一列到我现有的表，所以我怎么能改变表在sqlite数据库通过obj c，我使用以下代码插入数据到表中以同样的方式，我怎么能写updata表方法

- (void) InsertRecord {

if(addStmt == nil) {
    const char *sql = "insert into tbl_Users(FirstName,MiddleName) Values(?,?)";
    if(sqlite3_prepare_v2(database, sql, -1, &addStmt, NULL) != SQLITE_OK)
        NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(database));
}
sqlite3_bind_text(addStmt, 1, [strFirstName UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(addStmt, 2, [strMiddleName UTF8String], -1, SQLITE_TRANSIENT);
//sqlite3_bind_text(addStmt, 3, [strLogin UTF8String], -3, SQLITE_TRANSIENT);

if(SQLITE_DONE != sqlite3_step(addStmt))
    NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database));
else
    //SQLite provides a method to get the last primary key inserted by using sqlite3_last_insert_rowid
    //productID = sqlite3_last_insert_rowid(database);
//Reset the add statement.
sqlite3_reset(addStmt);

}

有谁能帮我吗，提前谢谢你

Answer 1

这可能有点用。头文件

NSString *databasePath;

。m文件//调用这些方法

    [self checkAndCreateDB ];
    [self alterDB];
-(void)checkAndCreateDB {
    NSString* databaseName = @"MasterDB.sqlite";
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [documentPaths objectAtIndex:0];
    databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
    BOOL success1;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    success1 = [fileManager fileExistsAtPath:databasePath];
    if(success1) return;
    NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:databaseName];
    [fileManager copyItemAtPath:databasePathFromApp toPath:databasePath error:nil];
}
-(void) alterDB{
    sqlite3 *database;
    sqlite3_stmt *statement; 
    if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
    {
        NSString *updateSQL = [NSString stringWithFormat: @"ALTER TABLE User ADD COLUMN testColumn TEXT"];
        const char *update_stmt = [updateSQL UTF8String];
        sqlite3_prepare_v2(database, update_stmt, -1, &statement, NULL);
        if(sqlite3_step(statement)==SQLITE_DONE) 
        {
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"DB altered" message:@"Success" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];    
            [alert show];
            [alert release];
            alert=nil;
        }
        else 
        {
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"DB Updation" message:@"DB not Altered" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];   
            [alert show];
            [alert release];
            alert=nil;
        }   
        // Release the compiled statement from memory
        sqlite3_finalize(statement);    
        sqlite3_close(database);
    }
}