Answer Posted / blue shark

JOIN:
-----

A Join is used for displaying columns with the same or
different names from different tables. The output displayed
will have all the columns shown individually. i.e. The
columns will be aligned next to each other.

UNION:
------

The UNION set operator is used for combining data from two
tables which have columns with the same datatype.
When a UNION is performed the data from both tables will be
collected in a single column having the same datatype.

For eg:

See the two tables shown below:

Table t1

Articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2

Table t2
manufacturer_id manufacturer
1 ABC Gmbh
2 DEF Co KG

Now for performing a JOIN type the query shown below

SELECT articleno, article, manufacturer
FROM t1 JOIN t2 ON (t1.manufacturer_id =
t2.manufacturer_id);

articelno article manufacturer
1 hammer ABC GmbH
2 screwdriver DEF Co KG

That is a join.

UNION means that you have to tables or resultset with the
same amount and type of columns and you add this to
tables/resultsets together. Look at this example:

Table year2006

Articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2

Table year2007

Articleno article price manufacturer_id
1 hammer 6 $ 3
2 screwdriver 7 $ 4

SELECT articleno, article, price, manufactruer_id
FROM year2006
UNION
SELECT articleno, article, price, manufacturer_id
FROM year2007

articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2
1 hammer 6 $ 3
2 screwdriver 7 $ 4

Hope this helps!

What is use of package in pl sql?

1009

---

What are inner and outer joins examples of both?

954

---

how to start mysql server? : Sql dba

1195

---

how to drop an existing view in mysql? : Sql dba

1060

---

How many sql statements are used?

1006

---

What is crud sql?

976

---

Can you selectively load only those records that you need? : aql loader

1044

---

What is a recursive stored procedure?

1175

---

How do I upgrade sql?

998

---

What is difference between stored function and application function?

1195

---

Explain the select statement in sql?

1107

---

Why use stored procedures?

1080

---

How to find 3rd highest salary of an employee from the employee table in sql?

1079

---

what is the difference between primary key and unique key? : Sql dba

1034

---

Does sql between include endpoints?

999

---