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Rule-Based Arguments

Use @{...} with the Rule mechanism to elegantly handle common dynamic command scenarios.

Only add name when it is not empty

select * from users where id > :id @{and, name = :name}

AND Rule

AND rule

select * from users where id > :id @{and, name = :name}

• When the named argument name is not null/empty, and name = ? is appended to the WHERE clause.
• Final SQL:
  • name empty: select * from users where id > ?
  • name present: select * from users where id > ? and name = ?

OR Rule

OR rule

select * from users where id > :id @{or, name = :name}

• When name is not null/empty, or name = ? is appended to the WHERE clause.
• Final SQL:
  • name empty: select * from users where id > ?
  • name present: select * from users where id > ? or name = ?

SET Rule

SET rule

update users set modify_time = ? @{set, status = :status} where id > :id

• When status is not null/empty, status = ? is appended to the SET clause.
• Final SQL:
  • status empty: update users set modify_time = ? where id > ?
  • status present: update users set modify_time = ?, status = ? where id > ?

IN Rule

IN rule

select * from users where status = true @{in,and id in :ids}

• If ids has 3 elements, the IN rule appends and id in (?, ?, ?); the number of placeholders matches the element count.
• Final SQL:
  • ids empty: select * from users where status = true
  • ids present: select * from users where status = true and id in (?, ?, ?)

About rules

• dbVisitor ships with many built-in rules for different needs.
• For details, see here.