SQL - SELECT all the records limiited to certain characters - sql

Question

I am pretty new to SQL so I desperately need support with the following matter:
one of the columns of the table I am querying contains very long and various text values: so, I would like to limit the output to some kinds only.
I would like to get as output of the query the same content, limited to [a-z][A-Z][0-9], so for example:
Original table: Hello /% World, 2019
Result query: Hello World 2019
Does anybody have any idea?
Thank you very much

Answer 1

Assuming regexp_replace is supported,
regexp_replace(column, '[^a-zA-Z0-9]', '')

Answer 2

You didn't mention which SQL engine you are using, but most engines support the string function REPLACE which can use to substitute any character you want with an empty string to remove it. You will have to nest several of these to get rid of the different characters. Check the documentation of your database engine for the syntax.
For example:
SELECT REPLACE(REPLACE('Hello /% World, 2019, '/', ''), '%','')
In general, I would argue that this is not the job of the database engine, and you can do it in your presentation layer.
HTH

Answer 3

$string = 'Hello /% World, 2019';
Strip all characters but letters and numbers from a PHP string:
$res = preg_replace("/[^a-zA-Z0-9]/", "", $string);
Strip all characters but letters, numbers, and whitespace:
$res = preg_replace("/[^a-zA-Z0-9\s]/", "", $string);

Answer 4

BEST OPTION: Remove all special characters leaving no spaces
SELECT REGEXP_REPLACE(your_column, '[^0-9A-Za-z]', '') AS newfield
FROM tablename;
Remove many characters, leaving spaces for the same number of characters removed
SELECT TRANSLATE(columnname,'!##$%^&*()',
' ' ) AS newfield
FROM tablename;
If you just want to replace one character
SELECT REPLACE('columnname', '%', '') AS newfield
From tablename;
If you are looking for something in particular (You want to find the words "Hello World 2019")
Select ‘Hello World 2019' AS newfield
From tablename
WHERE columnname like ‘Hello%’ AND columnname like ‘%World%’ AND columnname like ‘%2019’;
Assuming Hello is always the beginning and 2019 is always at the end and you want all the fields. If you want other fields, you might want those as well; like,
Select TableID, columnname, ‘Hello World 2019' AS newfield
From tablename
WHERE columnname like ‘Hello%’ AND columnname like ‘%World%’ AND columnname like ‘%2019’;