Redshift LEFT and RIGHT Functions and Examples

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  • Post last modified:March 29, 2023
  • Post category:Redshift
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Amazon Redshift LEFT and RIGHT functions are string functions which are useful when you want to get sub-string from the given raw string. For example, consider a fixed width file and you want to extract leftmost 10 numbers, you can use Redshift LEFT function with length as an argument. In this article, we will check Redshift LEFT and RIGHT functions with some examples.

Redshift LEFT and RIGHT Functions
Redshift LEFT and RIGHT Functions

Page Contents

Introduction to Redshift String Functions

One important feature of Amazon Redshift is its extensive support of string functions. These string functions allow users to manipulate and transform string data in various ways, including formatting, concatenation, and substring extraction. Some of the most commonly used string functions in Redshift include LEFT, RIGHT, SUBSTRING, CONCAT, and REPLACE.

The LEFT and RIGHT functions are string functions which are useful to manipulate the raw string. For instance, you can use these functions to cleanse the raw data.

Amazon Redshift LEFT and RIGHT Functions

The LEFT and RIGHT functions return the specified number of leftmost or rightmost characters from a character string or input string. Both left and right string returns a varchar string.

The returned number is a number of character not a byte.

Redshift LEFT Function

The Redshift LEFT function return the specified number of leftmost characters from a character string or input string.

Redshift LEFT Function Syntax

Below is the syntax of Redshift LEFT function:

LEFT ( string,  integer )

Where, string is input string and integer is number if characters to be returned.

Redshift LEFT Function Examples

There are many use case of LEFT functions in a data warehouse. Below are some of the examples.

select left ('012345678910', 5);
 left
-------
 01234
(1 row)

select left ('Redshift left Function is very useful', 23);
          left
-------------------------
 Redshift left Function
(1 row)

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Redshift RIGHT Function

The Redshift RIGHT function return the specified number of rightmost characters from a character string or input string.

Redshift RIGHT Function Syntax

Below is the syntax of Redshift RIGHT function:

RIGHT ( string,  integer )

Where, string is input string and integer is number if characters to be returned.

Redshift RIGHT Function Examples

There are many use case of right functions in a data warehouse. Below are some of the examples.

 select right ('012345678910', 5);
 right
-------
 78910
(1 row)

select right ('Redshift left Function is very useful', 12);
    right
--------------
  very useful
(1 row)

Redshift SUBSTR as a LEFT and RIGHT Functions Alternative

You can use SUBSTR as a left and right functions alternative. Below is the syntax:

SUBSTRING(string, start_position, number_characters )

You should provide start and number of characters to be returned.

For example,

select SUBSTR('ABCDED', 1, 2);
 substr
--------
 AB
(1 row)

select SUBSTR('ABCDED', 5, 2);
 substr
--------
 ED
(1 row)

Benefits of Left and Right functions in Redshift

The LEFT and RIGHT functions in Amazon Redshift are used to extract a specified number of characters from the beginning or end of a string, respectively. Following are some benefits of using these functions:

  • Data Cleaning: Sometimes, the data received from various sources may contain extraneous characters at the beginning or end of a string, such as spaces or other special characters. The LEFT and RIGHT functions can be used to remove these characters and clean the data before storing it in database tables.
  • Data Analytics: The Redshift LEFT and RIGHT functions can also be used to perform data analysis, such as grouping data based on the first or last character in a string field.
  • Data Manipulation: Amazon Redshift LEFT and RIGHT functions can be used to extract a specific portion of a string. This can be helpful in performing data manipulation operations.
  • Query optimization: Rarely, the LEFT and RIGHT functions can improve query performance by reducing the amount of data that needs to be processed.

In summery, the LEFT and RIGHT functions in Amazon Redshift are useful for data cleaning, data manipulation, data analysis, and query optimization in SQL.

Conclusion

In conclusion, the LEFT and RIGHT functions are essential string functions in Amazon Redshift that can be used to extract a specified number of characters from the beginning or end of a string, respectively. By leveraging these functions, users can efficiently manipulate strings to clean raw data. These functions are useful in data analysis and sometime helps in optimizing complex queries.

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Hope this helps 🙂

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