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which is Faster Union or Union All?
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Posted Date :
April 12, 2013
Union All is faster than union in SQL Server
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which is Faster Union or Union All?
What is the difference between UNION ALL Statement and UNION
The main difference between UNION ALL statement and UNION is UNION All statement is much faster than UNION.
Reason : Because UNION ALL statement does not look for duplicate rows, but on the other hand UNION statement does look for duplicate rows, whether or not they exist.
Difference between UNION and UNION in SQL ?
UNION : Doesn't return Duplicate Values.
UNION ALL: return All values (includes Duplicate Values)
Difference between:UNION and INTERSET?
UNION: OR operator (value is selected if it appears in either the first or the second statement)
INTERSET:AND operator (value is selected only if it appears in both statements).
What is difference between Union and Union All
Union will filter duplicate values where as union all will not filter duplicate values
What is the difference among UNION, MINUS and INTERSECT
UNION combines the results from 2 tables and eliminates duplicate records from the result set.
MINUS operator when used between 2 tables, gives us all the rows from the first table except the rows which are present in the second table.
INTERSECT operator returns us only the matching or common rows between 2 result sets.
What is the difference between UNION and UNION ALL
UNION and UNION ALL both unify for add two structurally similar data sets, but UNION operation returns only the unique records from the resulting data set whereas UNION ALL will return all the rows, even if one or more rows are duplicated to each other.
What is the difference between JOIN and UNION
SQL JOIN allows us to "lookup" records on other table based on the given conditions between two tables. For example, if we have the department ID of each employee, then we can use this department ID of the employee table to join with the department ID of department table to lookup department names.
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