What is the main difference between a UNION statement and a
UNION ALL statement?
1. A UNION statement eliminates duplicate rows; a UNION
ALL statement includes duplicate rows.
2. A UNION statement can be used to combine any number of
queries; a UNION ALL statement can be used to combine a
maximum of two queries.
3. A UNION statement can only combine queries that have
parallel fields in the SELECT list; a UNION ALL statement
can combine queries with differing SELECT list structures.
4. A UNION statement cannot be used with aggregate
functions; a UNION ALL statement can be used with aggregate
functions.
5. There is no difference between the two statements; they
are interchangeable.
Answers were Sorted based on User's Feedback
Answer / anil_abbireddy
1. A UNION statement eliminates duplicate rows; a UNION ALL
statement includes duplicate rows.
| Is This Answer Correct ? | 11 Yes | 0 No |
Answer / menan
A UNION statement eliminates duplicate rows; a UNION
ALL statement includes duplicate rows.
| Is This Answer Correct ? | 4 Yes | 0 No |
if i perform any operation on views such as insert, delete etc will my base table get affected?????
Which is faster joins or subqueries?
How to fetch values from testtable1 that are not in testtable2 without using not keyword?
How would you pass hints to the sql processor?
What found sql?
Why is sharding used?
Which constraints we can use while creating database in sql?
Mention what is the use of function "module procedure" in pl/sql?
what is cross join? : Sql dba
Can you sum a count in sql?
2. Select A.A from ( select 1 as from dual Union select 1 as from dual)A Full outer join ( select 1 B from dual Union select 2 B from dual)B On A.A=B.B
Why is sql better than hql?
Oracle (3253)
SQL Server (4518)
MS Access (429)
MySQL (1402)
Postgre (483)
Sybase (267)
DB Architecture (141)
DB Administration (291)
DB Development (113)
SQL PLSQL (3330)
MongoDB (502)
IBM Informix (50)
Neo4j (82)
InfluxDB (0)
Apache CouchDB (44)
Firebird (5)
Database Management (1411)
Databases AllOther (288)