php and mysql queries - php

Question

I'm creating a website where the user can add some information about multiple computers into a database.
In the mysql database I have 3 tables. TypeOfMachine, Software and Hardware. The only common thing they have is the NumberOfMachine.
I must create a page where the user can run reports showing devices that have a specific piece of software installed (user specified) or specific hardware (user specified) after he submitted the computer's info.
Any ideas how I can do this?
And how I can connect all 3 tables into one?
I thought about this code but i dont know what to put in WHERE. I have 10 variables. and I have to show all the computers with what the user has asked and their info as well!
$search1 = "
SELECT
TypeOfMachine.NumberOfMachine, TypeOfMachine.TypeOfMachine, TypeOfMachine.OS, Software.Software1, Software.Software2, Software.Software3, Hardware.SSD, Hardware.Harddisk, Hardware.MonitorSize, Hardware.Ram, Hardware.Rom, Hardware.Processor
FROM TypeOfMachine, Software, Hardware
WHERE
but i

Answer 1

You want to use a join. This example is based on the fact that you've said the NumberOfMachine field is present in all tables and is a common link between them:
SELECT
TypeOfMachine.NumberOfMachine,
TypeOfMachine.TypeOfMachine,
TypeOfMachine.OS,
Software.Software1,
Software.Software2,
Software.Software3,
Hardware.SSD,
Hardware.Harddisk,
Hardware.MonitorSize,
Hardware.Ram,
Hardware.Rom,
Hardware.Processor
FROM TypeOfMachine
LEFT JOIN Software
ON Software.NumberOfMachine = TypeOfMachine.NumberOfMachine
LEFT JOIN Hardware
ON Hardware.NumberOfMachine = TypeOfMachine.NumberOfMachine
WHERE
...

Answer 2

It's general question, I don't know which tables contains a spesific columns as indicator for all tables. It's about inner and outer join:
The two common types of joins are an inner join and an outer join. The difference between an inner and outer join is in the number of rows included in the results table.
Inner join: The results table produced by an inner join contains only rows that existed in both tables.
Outer join: The combined table produced by an outer join contains all rows that existed in one table with blanks in the columns for the rows that did not exist in the second table.
For instance, if table1 contains a row for Joe and a row for Sally, and table2 contains only a row for Sally, an inner join would contain only one row: the row for Sally. However, an outer join would contain two rows — a row for Joe and a row for Sally — even though the row for Joe would have a blank field for weight.
The results table for the outer join contains all the rows for one table. If any of the rows for that table don’t exist in the second table, the columns for the second table are empty. Clearly, the contents of the results table are determined by which table contributes all its rows, requiring the second table to match it.
Two kinds of outer joins control which table sets the rows and which must match: a LEFT JOIN and a RIGHT JOIN.
You use different SELECT queries for an inner join and the two types of outer joins. The following query is an inner join:
SELECT columnnamelist FROM table1,table2
WHERE table1.col2 = table2.col2
And these queries are outer joins:
SELECT columnnamelist FROM table1 LEFT JOIN table2
ON table1.col1=table2.col2
SELECT columnnamelist FROM table1 RIGHT JOIN table2
ON table1.col1=table2.col2
In all three queries, table1 and table2 are the tables to be joined. You can join more than two tables. In both queries, col1 and col2 are the names of the columns being matched to join the tables. The tables are matched based on the data in these columns. These two columns can have the same name or different names, but they must contain the same type of data.
For general concept you can use #Scrowler suggestion, or this one:
http://stackoverflow.com/questions/1204217/mysql-select-join-3-tables