Oracle 18c

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ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
CREATE TABLE table_name (
  col1 VARCHAR2(20),
  col2 VARCHAR2(100),
  col3 VARCHAR2(20),
  col4 VARCHAR2(20),
  col5 VARCHAR2(20),
  col6 VARCHAR2(20),
  col7 VARCHAR2(20)
);
INSERT INTO table_name (col1, col2)
  VALUES (1, 'key1:Val1;Key2:Val2;;;Key5:Val5');
1 rows affected

UPDATE table_name
  SET col3 = REGEXP_SUBSTR(Col2, '(;|^)key1:(.*?)(;|$)', 1, 1, 'i', 2),
      col4 = REGEXP_SUBSTR(Col2, '(;|^)key2:(.*?)(;|$)', 1, 1, 'i', 2),
      col5 = REGEXP_SUBSTR(Col2, '(;|^)key3:(.*?)(;|$)', 1, 1, 'i', 2),
      col6 = REGEXP_SUBSTR(Col2, '(;|^)key4:(.*?)(;|$)', 1, 1, 'i', 2),
      col7 = REGEXP_SUBSTR(Col2, '(;|^)key5:(.*?)(;|$)', 1, 1, 'i', 2)
1 rows affected

SELECT * FROM table_name;


COL1
COL2
COL3
COL4
COL5
COL6
COL7


1
key1:Val1;Key2:Val2;;;Key5:Val5
Val1
Val2
null
null
Val5


SELECT col1,
       col2,
       REGEXP_SUBSTR(Col2, '(;|^)key1:(.*?)(;|$)', 1, 1, 'i', 2) AS col3,
       REGEXP_SUBSTR(Col2, '(;|^)key2:(.*?)(;|$)', 1, 1, 'i', 2) AS col4,
       REGEXP_SUBSTR(Col2, '(;|^)key3:(.*?)(;|$)', 1, 1, 'i', 2) AS col5,
       REGEXP_SUBSTR(Col2, '(;|^)key4:(.*?)(;|$)', 1, 1, 'i', 2) AS col6,
       REGEXP_SUBSTR(Col2, '(;|^)key5:(.*?)(;|$)', 1, 1, 'i', 2) AS col7
FROM  table_name;


COL1
COL2
COL3
COL4
COL5
COL6
COL7


1
key1:Val1;Key2:Val2;;;Key5:Val5
Val1
Val2
null
null
Val5