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内联派生表

适用于 ✅ 开源版 ✅ 专业版 ✅ 企业版

内联派生表是一个表表达式，带有一个WHERE 子句，这两种情况都可以在很多情况下内联到调用查询中。

此功能的主要用例是动态 SQL，您可以在不影响调用站点的情况下向表中添加谓词，并且不会放弃类型安全。

-- In SQL, the derived table is inlined
SELECT
  BOOK.ID,
  BOOK.TITLE
FROM BOOK
WHERE BOOK.TITLE LIKE 'A%'

// This book reference can be supplied dynamically
Book aBooks = BOOK.where(BOOK.TITLE.like("A%"));

create.select(aBooks.ID, aBooks.TITLE)
      .from(aBooks)
      .fetch();

每当上下文需要时，内联派生表都会生成一个显式的派生表，例如，当在LEFT JOIN中使用时

-- In SQL, the derived table created explicitly
SELECT BOOK.ID, BOOK.TITLE
FROM AUTHOR
LEFT JOIN (
  SELECT * FROM BOOK WHERE BOOK.TITLE LIKE 'A%'
) BOOK
ON AUTHOR.ID = BOOK.AUTHOR_ID

// This book reference can be supplied dynamically
Book aBooks = BOOK.where(BOOK.TITLE.like("A%"));

create.select(AUTHOR.ID, aBooks.ID, aBooks.TITLE)
      .from(AUTHOR)
      .leftJoin(aBooks).on(AUTHOR.ID.eq(aBooks.AUTHOR_ID))
      .fetch();