Create function from SQL script by Liquibase

I think you need to add the endDelimiter clause in the Liquibase tag, based on the documentation found here

Below is an example

<changeSet author="newbie" id="function_rad2deg" dbms="mysql,h2">
    <sqlFile encoding="utf8" 
             path="sql/function_rad2deg.sql" 
             relativeToChangelogFile="true"  
             splitStatements="false" 
             stripComments="false"
             endDelimiter="\nGO"
    />
</changeSet>

Your SQL file with the above delimiter would then look like

DROP FUNCTION IF EXISTS rad2deg;
GO

CREATE FUNCTION rad2deg(rad DOUBLE)
RETURNS DOUBLE
BEGIN
    RETURN (rad * 180 / PI());
END
GO

Hope this helps

With above example there are two problems one is it will not work on h2 and 2 is splitStatements should be true:

<changeSet author="me" id="01_functions_mysql" dbms="mysql">
    <sqlFile encoding="utf8" path="sql/01_functions.mysql.sql" 
    relativeToChangelogFile="true" 
    splitStatements="true" 
    stripComments="false" 
    endDelimiter="\nGO" />
</changeSet>

and than something like this:

DROP FUNCTION IF EXISTS FIRST_DAY_THIS_MONTH;

GO

CREATE FUNCTION FIRST_DAY_THIS_MONTH (day date) 
RETURNS date
DETERMINISTIC
BEGIN 
  RETURN STR_TO_DATE  ( DATE_FORMAT    ( day,'%Y%m01' ),'%Y%m%d');
END

GO

If you are using yaml file then here is the configuration

changeSet:
  id: sqlFile-function
  author: sandeep
  logicalFilePath: baseFunctionScript
  changes:
  - sqlFile:
      dbms: mysql
      encoding: utf8
      endDelimiter: \nGO
      path: my/path/baseScripts.sql
      splitStatements: true
      stripComments: false

Make sure stripComments should be false else it will throw an error. I spent 4 hours because of it.