In current feature, it does not support for appending and trimming SQL key-word(e.g. WHERE, AND, SET) like as <where> and <set> provided by xml based scripting language.
So, we need to add the no-dynamic phrase (e.g. WHERE 1 = 1, SET id = id, etc ...) before dynamic parts. I think it is easy writing but it is troublesome rule.

I hope to be enabled to write as follow:

SELECT * FROM names /*[# mybatis:where]*/ WHERE /*[# th:if="${firstName} != null"]*/ firstName = /*[('#{firstName}')]*/ 'Taro' /*[/]*/ /*[# th:if="${lastName} != null"]*/ AND lastName = /*[('#{lastName}')]*/ 'Yamada' /*[/]*/ /*[/]*/