如何使用 regexp_replace 将 mysql 中的多个字符替换为特定字符？

Question

I am using regexp_replace to replace a field of type string having some special characters with '_' where ever those characters are present.

I am using

SELECT regexp_replace('name', ' |\-|\(|\)|\.', '_') from db.table;

Some values from the field 'name':

Pune Municipal Corp - Water
Kerala State Electricity Board Ltd. (KSEBL)
Paschim Gujarat Vij Company Limited (PGVCL)


What I want:

Pune_Municipal_Corp___Water
Kerala_State_Electricity_Board_Ltd___KSEBL_
Paschim_Gujarat_Vij_Company_Limited__PGVCL_

Answer 1

Try this

SELECT  regexp_replace(name, '[^a-zA-Z0-9_]', '_') 

db<>fiddle

Answer 2

I don't know what version of mysql you're using but, on mysql 8+ you can use the native REGEXP_REPLACE function.

Otherwise if the version which you're using don't support regexp replace, you could just create a function to do that.

Here is the function code:

DELIMITER $$

CREATE FUNCTION  `regex_replace`(pattern VARCHAR(1000),replacement VARCHAR(1000),original VARCHAR(1000))
RETURNS VARCHAR(1000)
DETERMINISTIC
BEGIN 
 DECLARE temp VARCHAR(1000); 
 DECLARE ch VARCHAR(1); 
 DECLARE i INT;
 SET i = 1;
 SET temp = '';
 IF original REGEXP pattern THEN 
  loop_label: LOOP 
   IF i>CHAR_LENGTH(original) THEN
    LEAVE loop_label;  
   END IF;
   SET ch = SUBSTRING(original,i,1);
   IF NOT ch REGEXP pattern THEN
    SET temp = CONCAT(temp,ch);
   ELSE
    SET temp = CONCAT(temp,replacement);
   END IF;
   SET i=i+1;
  END LOOP;
 ELSE
  SET temp = original;
 END IF;
 RETURN temp;
END$$

DELIMITER ;

Example using your regex and text:

mysql> select regex_replace('[ |\-|\(|\)|\.-]', '_', 'Pune Municipal Corp - Water Kerala State Electricity Board Ltd. (KSEBL) Paschim Gujarat Vij Company Limited (PGVCL)');

I got the code of the function here

Hope this helps!

Answer 3

You can simply use the translate to replace space and - with underscore( _ ) as follows:

Select translate(your_column, ' -', '__') from your_table

Db<>fiddle demo