mysql table column type as math formula

Anon

Usually when creating a table, column types are something like BLOB, INT, DATETIME, etc.

Instead of such column types, is it possible to make it a mathematical formula? The formula will include other columns in the table.

This kind of thing is easily done in Excel, where values in one column is automatically updated when other columns change.

Example: I have a table,

| colA | colB | colC |

Now I want to add another column that'll be type:

cos(col😎 * sin(colC) / ColA

TIA,
Richie.

Anon

Include the calculation in your select statement.

If you were using a decent DBMS instead of Mysql you could create a view for this.

Anon

I tried the select statement idea, but it didn't work.

$part1 = cos(deg2rad($lat)) cos(deg2rad($long)) cos(deg2rad(latitude)) cos(deg2rad(longitude));
$part2 = cos(deg2rad($lat)) sin(deg2rad($long)) cos(deg2rad(latitude)) sin(deg2rad(longitude));
$part1 = sin(deg2rad($lat)) sin(deg2rad($long));
$EQN = acos($part1 + $part2 + $part3) 3959;

$query = "SELECT latitude, longitude FROM zipcodes WHERE $EQN<$x";

latitude, longitude are columns inside the table, and $lat, $long, $x are constants.

The select statement does not return any values.

Can anybody see anything wrong with the above?

Anon

Actually, the correct code is:

$part1 = cos(deg2rad($lat)) cos(deg2rad($long)) cos(deg2rad(latitude)) cos(deg2rad(longitude));
$part2 = cos(deg2rad($lat)) sin(deg2rad($long)) cos(deg2rad(latitude)) sin(deg2rad(longitude));
$part3 = sin(deg2rad($lat)) sin(deg2rad($long));
$EQN = acos($part1 + $part2 + $part3) 3959;

$query = "SELECT latitude, longitude FROM zipcodes WHERE $EQN<$x";

Anon

I thought we went through this a couple of days ago.

The expressions being assigned to $part1 and $part2 are evaluated at the time the assignment is made, not when the "select" is run. You are trying to take the sine and cosine of the words 'latitude' and 'longitude'.

Anon

I know what you're saying tombath, but I don't have a way around the problem.

I can't get longitude, latitude, unless $eqn is calculated.

A viable solution as I see it now, is to assign a formula to a column, which is what I've asked in this thread.

Can mysql do what Excel does, where you assign a formula to a column?