Skip to content

Latest commit

 

History

History
234 lines (145 loc) · 12 KB

select-examples-transact-sql.md

File metadata and controls

234 lines (145 loc) · 12 KB
title description author ms.author ms.reviewer ms.date ms.service ms.subservice ms.topic ms.custom helpviewer_keywords dev_langs monikerRange
SELECT examples (Transact-SQL)
Examples of the SELECT Transact-SQL statement in the Database Engine.
VanMSFT
vanto
randolphwest
11/01/2023
sql
t-sql
reference
ignite-2024
parentheses [SQL Server]
GROUP BY clause, SELECT statement
query hints [SQL Server]
ALL keyword
ROLLUP operator
SELECT statement [SQL Server], examples
correlated subqueries, SELECT statement
SELECT INTO statement
ORDER BY clause [Transact-SQL]
GROUPING function
index hints [SQL Server]
HAVING clause, SELECT statement
DISTINCT keyword
CUBE operator
UNION operator [SQL Server]
computed sums
WHERE clause, SELECT statement
TSQL
=azuresqldb-current || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqldb-mi-current || =fabric

SELECT examples (Transact-SQL)

[!INCLUDE SQL Server Azure SQL Database Azure SQL Managed Instance FabricSQLDB]

This article provides examples of using the SELECT statement.

[!INCLUDE article-uses-adventureworks]

A. Use SELECT to retrieve rows and columns

The following example shows three code examples. This first code example returns all rows (no WHERE clause is specified) and all columns (using the *) from the Product table in the [!INCLUDE ssSampleDBobject] database.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_1.sql":::

This example returns all rows (no WHERE clause is specified), and only a subset of the columns (Name, ProductNumber, ListPrice) from the Product table in the [!INCLUDE ssSampleDBobject] database. Additionally, a column heading is added.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_2.sql":::

This example returns only the rows for Product that have a product line of R and that have days to manufacture that is less than 4.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_3.sql":::

B. Use SELECT with column headings and calculations

The following examples return all rows from the Product table. The first example returns total sales and the discounts for each product. In the second example, the total revenue is calculated for each product.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_4.sql":::

This is the query that calculates the revenue for each product in each sales order.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_5.sql":::

C. Use DISTINCT with SELECT

The following example uses DISTINCT to prevent the retrieval of duplicate titles.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_6.sql":::

D. Create tables with SELECT INTO

The following first example creates a temporary table named #Bicycles in tempdb.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_7.sql":::

This second example creates the permanent table NewProducts.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_8.sql":::

E. Use correlated subqueries

A correlated subquery is a query that depends on the outer query for its values. This query can be executed repeatedly, one time for each row that could be selected by the outer query.

The first example shows queries that are semantically equivalent to illustrate the difference between using the EXISTS keyword and the IN keyword. Both are examples of a valid subquery that retrieves one instance of each product name for which the product model is a long sleeve logo jersey, and the ProductModelID numbers match between the Product and ProductModel tables.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_9.sql":::

The next example uses IN and retrieves one instance of the first name and family name of each employee for which the bonus in the SalesPerson table is 5000.00, and for which the employee identification numbers match in the Employee and SalesPerson tables.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_10.sql":::

The previous subquery in this statement can't be evaluated independently of the outer query. It requires a value for Employee.EmployeeID, but this value changes as the [!INCLUDE ssDEnoversion] examines different rows in Employee.

A correlated subquery can also be used in the HAVING clause of an outer query. This example finds the product models for which the maximum list price is more than twice the average for the model.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_11.sql":::

This example uses two correlated subqueries to find the names of employees who sold a particular product.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_12.sql":::

F. Use GROUP BY

The following example finds the total of each sales order in the database.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_13.sql":::

Because of the GROUP BY clause, only one row containing the sum of all sales is returned for each sales order.

G. Use GROUP BY with multiple groups

The following example finds the average price and the sum of year-to-date sales, grouped by product ID and special offer ID.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_14.sql":::

H. Use GROUP BY and WHERE

The following example puts the results into groups after retrieving only the rows with list prices greater than $1000.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_15.sql":::

I. Use GROUP BY with an expression

The following example groups by an expression. You can group by an expression if the expression doesn't include aggregate functions.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_16.sql":::

J. Use GROUP BY with ORDER BY

The following example finds the average price of each type of product and orders the results by average price.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_17.sql":::

K. Use the HAVING clause

The first example that follows shows a HAVING clause with an aggregate function. It groups the rows in the SalesOrderDetail table by product ID and eliminates products whose average order quantities are five or less. The second example shows a HAVING clause without aggregate functions.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_18.sql":::

This query uses the LIKE clause in the HAVING clause.

USE AdventureWorks2022;
GO
SELECT SalesOrderID, CarrierTrackingNumber
FROM Sales.SalesOrderDetail
GROUP BY SalesOrderID, CarrierTrackingNumber
HAVING CarrierTrackingNumber LIKE '4BD%'
ORDER BY SalesOrderID ;
GO

L. Use HAVING and GROUP BY

The following example shows using GROUP BY, HAVING, WHERE, and ORDER BY clauses in one SELECT statement. It produces groups and summary values but does so after eliminating the products with prices over $25 and average order quantities under 5. It also organizes the results by ProductID.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_19.sql":::

M. Use HAVING with SUM and AVG

The following example groups the SalesOrderDetail table by product ID and includes only those groups of products that have orders totaling more than $1000000.00 and whose average order quantities are less than 3.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_20.sql":::

To see the products with total sales greater than $2000000.00, use this query:

:::code language="sql" source="codesnippet/tsql/select-examples-transact_21.sql":::

If you want to make sure there are at least 1,500 items involved in the calculations for each product, use HAVING COUNT(*) > 1500 to eliminate the products that return totals for fewer than 1500 items sold. The query looks like this:

:::code language="sql" source="codesnippet/tsql/select-examples-transact_22.sql":::

N. Use the INDEX optimizer hint

The following example shows two ways to use the INDEX optimizer hint. The first example shows how to force the optimizer to use a nonclustered index to retrieve rows from a table. The second example forces a table scan by using an index of 0.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_23.sql":::

M. Use OPTION and the GROUP hints

The following example shows how the OPTION (GROUP) clause is used with a GROUP BY clause.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_24.sql":::

O. Use the UNION query hint

The following example uses the MERGE UNION query hint.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_25.sql":::

P. Use a UNION

In the following example, the result set includes the contents of the ProductModelID and Name columns of both the ProductModel and Gloves tables.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_26.sql":::

Q. Use SELECT INTO with UNION

In the following example, the INTO clause in the second SELECT statement specifies that the table named ProductResults holds the final result set of the union of the designated columns of the ProductModel and Gloves tables. The Gloves table is created in the first SELECT statement.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_27.sql":::

R. Use UNION of two SELECT statements with ORDER BY

The order of certain parameters used with the UNION clause is important. The following example shows the incorrect and correct use of UNION in two SELECT statements in which a column is to be renamed in the output.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_28.sql":::

S. Use UNION of three SELECT statements to show the effects of ALL and parentheses

The following examples use UNION to combine the results of three tables that all have the same five rows of data. The first example uses UNION ALL to show the duplicated records, and returns all 15 rows. The second example uses UNION without ALL to eliminate the duplicate rows from the combined results of the three SELECT statements, and returns five rows.

The third example uses ALL with the first UNION and parentheses enclose the second UNION that isn't using ALL. The second UNION is processed first because it's in parentheses, and returns five rows because the ALL option isn't used and the duplicates are removed. These five rows are combined with the results of the first SELECT by using the UNION ALL keywords. This example doesn't remove the duplicates between the two sets of five rows. The final result has 10 rows.

:::code language="sql" source="codesnippet/tsql/select-examples-transact_29.sql":::

Related content