Answer / samy

Union:
combine two tables and common values to be retrieved no
duplicate values

Union All:

All the values to be retrieved when combine two table.
(duplicate values)

Answer / shyam

Union: It will combine the output of two or more queries &
it will eliminate duplicate values.

Union all:It will combine the output of two or more queries
& it will not eliminate duplicate values.

Answer / ramesh raja

UNION: combine distinct values between two tables
UNION ALL : combine all values and also duplicates values
between the two tables

Answer / dinesh sharma

Union:Only Select Distinct Value
Union All:Select All Values Using Duplicate
All Selected Columns Must Have Same DataType
Example:
Table 1 : First,Second,Third,Fourth,Fifth
Table 2 : First,Second,Fifth,Sixth

Answer / shabanafazal

in case of 'union' the data of two tables are combined
together with no repetition where as incase of 'union all'
repetition of data is done e.g in table 'A' we have name
saad three times and in 'B' table name 'ssad' is present
one time then in case of 'union' 'saad' is appeard once
(when union of table 'A' and 'B' is done). where as in case
of 'union all' the name 'saad' will repeated four times.

Answer / dinesh waitage

1)Union is used to select distinct values from two tables
where as union all is used to select all values including
duplicates from the tables.

2)UNION - returns on Distinct rows/Slower in performance
UNION ALL.

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