How Can I Extract Digits from Alphanumeric Strings in MySQL?
Extract numbers from alphanumeric strings in MySQL
In database programming, extracting specific data from unstructured or mixed-type strings is a common task. MySQL provides a variety of functions and techniques for this purpose, including the ability to separate numbers from strings.
One way to extract a number from a string is to take advantage of MySQL's cast functionality. By using the CAST() function, you can implicitly convert a string to a numeric type, discarding non-numeric characters. For example, CAST('1234abc' AS UNSIGNED) returns 1234.
Another way is to use a custom function. You can create a reusable solution for extracting numbers by defining a function that iterates over the input string, checks the numeric value of each character, and concatenates the numbers into a new string. Consider the following function:
CREATE FUNCTION `ExtractNumber`(in_string VARCHAR(50))
RETURNS INT
NO SQL
BEGIN
DECLARE ctrNumber VARCHAR(50);
DECLARE finNumber VARCHAR(50) DEFAULT '';
DECLARE sChar VARCHAR(1);
DECLARE inti INTEGER DEFAULT 1;
IF LENGTH(in_string) > 0 THEN
WHILE(inti <= LENGTH(in_string)) DO
SET sChar = SUBSTR(in_string, inti, 1);
IF sChar BETWEEN '0' AND '9' THEN
SET finNumber = CONCAT(finNumber, sChar);
END IF;
SET inti = inti + 1;
END WHILE;
RETURN CAST(finNumber AS UNSIGNED);
ELSE
RETURN 0;
END IF;
END
After defining a function, you can call it in a query to extract numbers from any string. For example, the following query will return the number 1234:
SELECT ExtractNumber("abc1234def") AS number;The above is the detailed content of How Can I Extract Digits from Alphanumeric Strings in MySQL?. For more information, please follow other related articles on the PHP Chinese website!
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