What does the GROUP BY function do in SQL?

The GROUP BY statement groups rows that have the same values into summary rows, like “find the number of customers in each country”. The GROUP BY statement is often used with aggregate functions ( COUNT() , MAX() , MIN() , SUM() , AVG() ) to group the result-set by one or more columns.

How does GROUP BY work in SQL Server?

The GROUP BY clause in SQL Server allows grouping of rows of a query. Generally, GROUP BY is used with an aggregate SQL Server function, such as SUM, AVG, etc. In addition, the GROUP BY can also be used with optional components such as Cube, Rollup and Grouping Sets.

What is the use of GROUP BY and order by in SQL?

To summarize, the key difference between order by and group by is: ORDER BY is used to sort a result by a list of columns or expressions. GROUP BY is used to create unique combinations of a list of columns that can be used to form summaries.

How does GROUP BY query work?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group.

What does union statement do?

The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements. It does not remove duplicate rows between the various SELECT statements (all rows are returned). Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.

What is the use of GROUP BY and having clause?

The HAVING clause is used instead of WHERE with aggregate functions. While the GROUP BY Clause groups rows that have the same values into summary rows. The having clause is used with the where clause in order to find rows with certain conditions. The having clause is always used after the group By clause.

What is the purpose of GROUP BY command How is it different from ORDER BY command give example?

Group by statement is used to group the rows that have the same value. Whereas Order by statement sort the result-set either in ascending or in descending order. 2. It may be allowed in CREATE VIEW statement.

Can we use GROUP BY without aggregate function?

You can use the GROUP BY clause without applying an aggregate function. In this case, the GROUP BY works like the DISTINCT clause that removes duplicate rows from the result set.

What does GROUP BY and ORDER BY do?

Does SQL Union remove duplicates?

SQL Union All Operator Overview The SQL Union All operator combines the result of two or more Select statement similar to a SQL Union operator with a difference. The only difference is that it does not remove any duplicate rows from the output of the Select statement.