What is the Difference between Union and All Union
The structured query language commonly known as SQL is one of the widely used and most efficient and liked data base structure. It is query driven i.e. the queries or commands are written down and executed to get the results. There are many queries to make tables as well as add and create records, to extract values from different tables etc. Two such queries (or commands) are Union and All Union. There is a common word in both title but they don’t function alike.
Union
Union in the command in the SQL which combines the given set of data with another set but the results show only one answer which means that the first set’s values are executed while others are not included in the results. Actually, it is used to erase the similar data from the storage. For example if two tables have same value “1” with Union query, the resulting column will show “1” only once. This means the repetition of data is avoided.
All Union
The All Union command appends diverse values from different tables. For example the table one and two both have “1” and with union all, the resulting column will show “1” twice. So it’s simply to join two sets to get the desired results. It repeats the records as many times as they appear in the data base.
Union vs All Union
In simple words, Union query works to erase the repetition where as All Union query repeats the record as many times as they appear in the data base. The use of Union query is suitable only when repeated records are to be avoided but All Union query is needed when actual records or entries are needed. Union query executes to show alike records only once so the use of it may be destructive in many data assessments whereas All Union does not losses any entry and hence it is better to use it when data assessment is required.
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