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Introduction
Teradata SQL lacks a built-in function to determine the ASCII code of a character. But fear not, for there exists a query workaround to this dilemma. This blog post will guide you through the process of using a straightforward SQL query in Teradata to find the ASCII code of a character.
The solution is as follows:
We use the Teradata SQL function CHAR2HEXINT to obtain a hexadecimal value for a character. Our objective is to convert this hexadecimal value to its decimal counterpart, which signifies the character's ASCII code.
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This SQL query accomplishes the task.
SELECT
CASE SUBSTRING(CHAR2HEXINT('B') FROM 3 FOR 1)
WHEN '0' THEN 0
WHEN '1' THEN 1
WHEN '2' THEN 2
WHEN '3' THEN 3
WHEN '4' THEN 4
WHEN '5' THEN 5
WHEN '6' THEN 6
WHEN '7' THEN 7
WHEN '8' THEN 8
WHEN '9' THEN 9
WHEN 'A' THEN 10
WHEN 'B' THEN 11
WHEN 'C' THEN 12
WHEN 'D' THEN 13
WHEN 'E' THEN 14
WHEN 'F' THEN 15
END * 16 +
CASE SUBSTRING(CHAR2HEXINT('B') FROM 4 FOR 1)
WHEN '0' THEN 0
WHEN '1' THEN 1
WHEN '2' THEN 2
WHEN '3' THEN 3
WHEN '4' THEN 4
WHEN '5' THEN 5
WHEN '6' THEN 6
WHEN '7' THEN 7
WHEN '8' THEN 8
WHEN '9' THEN 9
WHEN 'A' THEN 10
WHEN 'B' THEN 11
WHEN 'C' THEN 12
WHEN 'D' THEN 13
WHEN 'E' THEN 14
WHEN 'F' THEN 15
END
Using a CASE statement, the query extracts two hexadecimal digits with the SUBSTRING function and converts them to decimal values. It then calculates the character's ASCII code by multiplying the first digit's decimal value by 16 and adding the second digit's decimal value.
Conclusion
Teradata SQL lacks a dedicated feature for determining the ASCII code of a given character. However, this blog post offers a straightforward and efficient workaround for this issue. By utilizing the CHAR2HEXINT function and performing basic arithmetic operations, you can effectively determine the ASCII code of any character within your Teradata SQL queries.
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Written by Roland Wenzlofsky, founder of DWHPro and author of Teradata Query Performance Tuning. DWHPro has helped data warehouse practitioners for 15+ years.