如何从多个表中选择*

Question

I have two tables, table1 and table2. table1 has 2 rows. table2 has 3 rows. so, totally table1 and table2 have 5 rows. I want to show the 5 rows by selecting table1 and table2 at a time. how todo? can you help me please. don't add any where clause.

Answer 1

depends on what the table structure is. if you have a PK > FK relationship you can join the tables like so

SELECT stuff
FROM table1 t1
JOIN table2 t2 ON t1.someID = t2.someID

if there is no correlation then you can use a UNION

SELECT stuff 
FROM table1
UNION
SELECT stuff
FROM table2

One thing to note about using a UNION. the columns have to match so if you have the same type of data in both tables this works fine or else you will have to specify which columns to be selected out.