Answer Posted / somashekhar m

Union : The union operator combines the results of two or
more queries into a single result set. But no.of columns
must match in both/all the queries (and also the order)
which are used for union.
Union -- returns with no duplicate rows
Union all -- retruns with duplicate rows (No. of rows
returned = No. of rows in Query1 + No. of rows in Query 2)
Union is a set operator.
You cannot use the union operator within a create view
statement.

You cannot use the union operator on text and image columns.

You cannot use the for browse clause in statements
involving the union operator.

Joins: Joins are used to extract information from more than
one table based on the related column/coloums (PK and RFK)
any no. of rows can be retrived based on matching matching
colums. Different types of joins are Inner join=equi join=
join, outer join(Right outer join/right join, Left outer
join/ left join), Cross join, and full outer join/outer join

How do you define a foreign key?

938

---

What are sql queries used for?

979

---

how to use regular expression in pattern match conditions? : Sql dba

963

---

what are wild cards used in database for pattern matching ? : Sql dba

1076

---

What are the benefits of stored procedures?

997

---

How do you update f as m and m as f from the below table testtable?

1789

---

what are null values? : Sql dba

900

---

Is sql better than excel?

1060

---

What is the most common sql injection tool?

994

---

How do I find duplicates in two columns?

1057

---

Explain how can you save or place your msg in a table?

981

---

What is Difference Between Unique and Primary Key Constraints?

1058

---

What are the features of pl sql?

1013

---

Is drop table faster than truncate?

940

---

Why do we need view in sql?

932

---