SQL Server BasicsWhat is SQL Server database?What is RDBMS?What is Normalization?Why we use Denormalization?What_is_SQL?What is PL/SQL?Difference between SQL and PL/SQLDatabase TableOne to One RelationshipOne to Many RelationshipMany to Many RelationshipMany to One RelationshipString Data TypesNumber Data TypesDate Data TypesOther Data TypesCreate DatabaseDrop DatabaseCreating and Managing Users in SQL ServerCreate TableAlter TableDrop TableConstraints in SQL serverPrimary KeyForeign KeyUnique KeyCandidate KeyComposite KeyDifference between primary key and candidate keyPrimary key and foreign key relationshipSurrogate KeyCascading Referential Integrity ConstraintsSelf Referential Integrity ConstraintsInsert into statementInsert multiple recordsUpdate statementDelete statementTruncate statementDifference between Delete and TruncateAlias in SQL ServerSelect statementSelect DistinctSelect TopSelect IntoNull Functions(ISNULL(),NULLIF(),COALESCE())Sub QueryIdentity ColumnSequence objectDifference between sequence and identity columnSQL Server ClausesWHERE ClauseOrder By ClauseTop N ClauseGroup By ClauseHaving ClauseDifference between Where and HavingSQL Server OperatorsArithmetic OperatorsComparison OperatorsLogical OperatorsBitwise OperatorsAny OperatorsAll OperatorsUnion OperatorsUnion All OperatorsDifference between Union and Union AllIntersect OperatorExcept OperatorDifference between Except and IntersectJoinsInner JoinLeft JoinRight JoinFull JoinSelf JoinCross JoinViewsWhat are views?Create views using SSMSIndexed ViewsComplex ViewsCheck Option in ViewCheck Encryption in ViewSchema Binding Option in ViewRead-only ViewsUpdatable ViewsAdvantages and disadvantages of viewsCreate multiple views on one tableCan we implement index on views?Can we Perform Insert, update, delete operation on views?Stored Procedure and FunctionsWhat are Stored Procedures?Why we use stored procedures?Passing parameters to Stored procedureUser-Defined FunctionsDifference between UDF and Stored procedurePre-Defined Functions@@Indentity and Scope_IndentityNULLIF, ISNULL and COALESCE
Previous
Next

SQL - Union All Operator

Here's an example to demonstrate the usage of the UNION ALL operator in SQL Server:

Consider two tables, "Employees" and "Customers", with the following structures:

Table: Employees
ID Name Department
1 John HR
2 Jane Sales
3 Mike IT
Table: Customers
ID Name Location
1 Lisa New York
2 Tom London
3 Sarah Paris

To combine the result sets of both tables, you can use the UNION ALL operator as follows:


SELECT ID, Name, Department
FROM Employees
UNION ALL
SELECT ID, Name, Location
FROM Customers;

The above query will merge the result sets of the two SELECT statements and return a single result set, including all rows from both tables. Here's the expected output:

ID Name Department
1 John HR
2 Jane Sales
3 Mike IT
1 Lisa New York
2 Tom London
3 Sarah Paris

As you can see, the result set includes all rows from the "Employees" table and all rows from the "Customers" table, without removing any duplicates. The column names, data types, and order must match in both SELECT statements for the UNION ALL operation to work correctly.

Remember that the UNION ALL operator does not eliminate duplicate rows, which can be useful when you want to include all rows from multiple tables or queries, even if there are duplicates.

Previous
Next