redshift variable assignment

Redshift SELECT INTO Variable – Example

• Post author: Vithal S
• Post last modified: December 13, 2021
• Post category: Redshift
• Reading time: 4 mins read

The relational database that supports procedural language allows you to assign a value to local variable using SELECT statement within stored procedures. The databases such as Teradata , Oracle supports SELECT INTO clause to assign a value to a local variable. In this article, we will check how to assign a subquery value to a local variable using Redshift SELECT INTO clause within Stored Procedures .

Redshift SELECT INTO Variable

The  SELECT   INTO  statement in Redshift retrieves data from one or more database tables, and assigns the selected values to variables. You can use SELECT INTO to assign a previously declared variable within a stored procedure or a RECORD type variable .

Redshift also selects rows defined by any query and inserts them into a new table. You can specify whether to create a temporary or a persistent table. This syntax is inline with Microsoft SQL Server T-SQL SELECT INTO syntax.

Redshift SELECT INTO Variable Examples

Following Redshift stored procedure uses the SELECT INTO statement to retrieve data from “TEST2” table and assign the selected values to variables.

Note that, you can use Redshift SELECT INTO clause to assign a variable only within a stored procedure. The statement is not supported outside stored procedures.

Redshift SELECT INTO New Table

Amazon Redshift SELECT INTO clause also selects rows returned by any query and inserts them into a new table. You can specify whether to create a temporary or a persistent table.

For example, following query sSelect all of the rows from the EVENT table and create a NEWEVENT permanent table.

and following example select the result of an aggregate query into a temporary table called PROFITS:

Related Articles,

• Redshift Dynamic SQL Queries and Examples
• How to Create and Use Redshift Cursor Variable? – Examples
• Redshift Stored Procedure Return Result Set – Working Example
• Redshift Conditional Statements – IF, LOOP, WHILE, FOR, CONTINUE and EXIT

Hope this helps 🙂

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Declaring Variables with AWS Redshift Query: A Practical Example

Abstract: In this article, we'll explore how to declare variables using AWS Redshift queries. We'll provide a practical example to help you understand the process.

Declaring Variables in AWS Redshift Query: A Practical Example

In this article, we will discuss how to declare variables in AWS Redshift query using a practical example. We will cover key concepts, provide detailed context, and use subtitles to make the topic easy to understand.

Introduction

AWS Redshift is a fully managed, petabyte-scale data warehouse service in the cloud. It enables users to analyze data using SQL and business intelligence tools, and delivers fast query and analysis performance for large datasets.

Declaring variables in AWS Redshift query is a useful technique that allows users to reuse values and simplify complex queries. In this example, we will declare a variable using the INSERT statement and use it in a SELECT statement.

Practical Example

Let's say we want to insert data into the segmentation table with the following schema:

• import_date : date
• id : integer
• orders : integer
• qty : integer
• value : double precision

We want to declare a variable td to represent the current date and use it in the SELECT statement to filter the data. Here's how we can do it:

In this example, we declare a variable td of type date and set its value to the current date using the SET statement. We then use the td variable in the SELECT statement to filter the data from some_table and insert it into the segmentation table.

Declaring variables in AWS Redshift query is a useful technique that allows users to reuse values and simplify complex queries. In this example, we have demonstrated how to declare a variable using the INSERT statement and use it in a SELECT statement. By using variables, we can make our queries more readable, maintainable, and efficient.

• AWS Redshift Documentation: Declare Variables
• AWS Redshift Documentation: CREATE TABLE
• AWS Redshift Documentation: INSERT
• AWS Redshift Documentation: SELECT
• Reference Type: Documentation

Tags: :  AWS Redshift SQL Database Variables

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• Data Warehousing

Redshift SELECT INTO 101: Syntax, Usage, and Examples Simplified

A relational database that supports procedural language allows you to assign a value to a local variable within stored procedures by using the SELECT statement. Teradata and Oracle databases, for example, support the SELECT INTO clause for assigning a value to a local variable.

In this article, we’ll look at how to use the Redshift SELECT INTO clause within Stored Procedures to assign a subquery value to a local variable.

In Redshift , the SELECT INTO statement retrieves data from one or more database tables and assigns the values to variables. To assign a previously declared variable within a stored procedure or a RECORD type variable, use the Redshift SELECT INTO.

Table of Contents

Introduction to Amazon Redshift

Amazon Redshift is a petabyte-scale data warehouse solution powered by Amazon Web Services . It is also used for large database migrations because it simplifies data management.

SELECT INTO Variable in Redshift

In Redshift, the SELECT INTO statement retrieves data from one or more database tables and assigns the values to variables. To assign a previously declared variable within a stored procedure or a RECORD type variable, use the Redshift SELECT INTO .

Redshift SELECT INTO Syntax

Redshift select into example.

Redshift also selects and inserts rows from any query into a new table. You can choose between creating a temporary and a persistent table. This syntax is similar to the T-SQL SELECT INTO syntax used in Microsoft SQL Server .

Rows defined by any query are selected and inserted into a new table. You can choose between creating a temporary and a persistent table.

See below for more information on the parameters of this command.

• WITH : A WITH clause is an optional clause that comes before a query’s SELECT list. WITH specifies one or more common table expressions.
• SELECT : The SELECT list specifies the columns, functions, and expressions that the query should return. The query’s output is represented by the list.
• FROM: A query’s FROM clause lists the table references (tables, views, and subqueries) from which data is selected.
• WHERE : The WHERE clause includes conditions that either joins tables or apply predicates to table columns.
• GROUP BY: The GROUP BY clause specifies the query’s grouping columns.
• HAVING: The HAVING clause adds a condition to the intermediate grouped result set returned by a query.
• UNION, INTERSECT & EXCEPT: The set operators UNION, INTERSECT, and EXCEPT are used to compare and merge the results of two separate query expressions.
• ORDER BY: The ORDER BY clause sorts a query’s result set.

Create a NEW EVENT table by selecting all of the rows from the EVENT table:

Enter the aggregate query result into a temporary table called PROFITS:

Another Example

• This blog goes into great detail about the Redshift SELECT INTO statement.
• It also provides an overview of Amazon Redshift before delving into the Redshift SELECT INTO statement. Utilize Redshift’s capabilities to select data into variables, enabling dynamic and efficient data processing.
• The Redshift SELECT INTO command is simple to use and follows the PostgreSQL querying protocol. However, the user should be aware of some limitations. Most of the time, the query validation will not return an error. It may carry out its own automatic conversions.

Sarthak is a skilled professional with over 2 years of hands-on experience in JDBC, MongoDB, REST API, and AWS. His expertise has been instrumental in driving Hevo's success, where he excels in adept problem-solving and superior issue management. Sarthak's technical proficiency and strategic approach have consistently contributed to optimizing operations and ensuring seamless performance, making him a vital asset to the team.

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Redshift variable hack.

Being a data warehouse , Redshift from AWS doesn’t provide the same level of programming platform that you may have had the luxury of using.

The concept of variables in Redshift is non existant however with this clever hack you can fake your way into some variable based information.

The same trick can be achieved using CREATE TEMP TABLE also. The temporary table version will allow you to use your variables outside of the context of that one query. As above, the variables are bound to the CTE feeding the query.

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Amazon Redshift RSQL variables

Some keywords act as variables in RSQL. You can set each to a specific value, or re-set the value. Most are set with \rset , which has an interactive mode and a batch mode. Commands may be defined in lower or upper case.

ACTIVITYCOUNT

Indicates the number of rows affected by the last submitted request. For a data-returning request, this is the number of rows returned to RSQL from the database. The value is 0 or a positive integer. The maximum value is 18,446,744,073,709,551,615.

The specially treated variable ACTIVITYCOUNT is similar to the variable ROW_COUNT . However, ROW_COUNT doesn't report a count of affected rows to the client application at command completion for SELECT , COPY or UNLOAD . But ACTIVITYCOUNT does.

activitycount_01.sql:

Console output:

Assigns severity levels to errors. Use the severity levels to determine a course of action. If the ERRORLEVEL command has not been used, its value is ON by default.

errorlevel_01.sql:

HEADING and RTITLE

Enables users to specify a header that appears at the top of a report. Header specified by the RSET RTITLE command automatically includes the current system date of the client computer.

rset_heading_rtitle_02.rsql content:

Designates a maximum error-severity level beyond which RSQL terminates job processing. Return codes are integer values that RSQL returns to the client operating system after completing each job or task. The value of the return code indicates the completion status of the job or task. If a script contains a statement that produces an error-severity level greater than the designated maxerror value, RSQL immediately exits. Therefore, to have RSQL exit on an error-severity level of 8, use RSET MAXERROR 7 .

maxerror_01.sql content:

Enables users to specify whether to apply settings for the formatting commands.

rset_rformat.rsql content:

Gets the number of records affected by the previous query. It's typically used to check a result, like in the following code fragment:

TITLEDASHES

This control enables users to specify whether a line of dash characters is to be printed above the column data returned for SQL statements.

Sets the output format to wrapped and specifies the target width for each line in a report. Without a parameter, it returns the current settings for both the format and target width.

rset_width_01.rsql content:

Example with parameter:

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