Question

No experience in database design. I have a following situation:
A table with 5 entries.

<DeviceIdentificationstr, data1, data2, data3.... data 5>

A table can have more than one device information.
I have designed something like this:

create table mytable (
  sNo integer PRIMARY KEY,
  DeviceIdentificationStr TEXT,
  data1 integer,
  data2 TEXT, ....)

Consider the following Scenario:

Record 1:    1, "Device1", "data1",  20, "data2", "data3"....
Record 2:    2, "Device2", "data1",  120, "data2", "data3"....
Record 3:    3, "Device2", "data1",  220, "data2", "data3"....
Record 4:    4, "Device1", "data1",  230, "data2", "data3"....

Here Device1 and Device2 are repeated all the time.

Are there any alternative way to design a table? Or is this the only way to go?

Also, i need to query something like: :Get all records of “Device1”.

Answer 1

You can perform so called normalization: create another table devices:

CREATE TABLE devices (
    device_id INTEGER PRIMARY KEY,
    DeviceIdentificationStr TEXT,
    DeviceMemory INTEGER,
    -- add more fields that describe device properties...
);

Change first table to be:

CREATE TABLE mytable (
    sNo INTEGER PRIMARY KEY,
    device_id INTEGER,
    data1 integer,
    data2 TEXT,
    ...
)

Now, you can use joins to get desired information, like this:

SELECT m.*,
    d.DeviceMemory,
    ...
FROM mytable m
    JOIN devices d USING (device_id)
WHERE d.DeviceIdentificationStr = 'mydevice'