fmdb 数据库升级-----增加表字段

//判断字段是否存在  

-(void)addColumnToTable:(NSString *)tableName ColumnName:(NSString *)column{

    if ((tableName == nil) || (column == nil)) 

    {

        return;

    }

    BOOL bExist = [db columnExists:column inTableWithName:tableName];

    if (!bExist) {

        NSString *sql = [NSString stringWithFormat:@"ALTER TABLE %@ ADD %@ text",tableName,column];  

        [db executeUpdate:sql]; 

    }

}