Question

从PreparedStatement开始，似乎参数化SQL语句只允许开发人员使用?和PreparedStatement.setX(index, value)来指定位置参数：

PreparedStatement statement = connection.prepareStatement("select * from something where id = ?;");
statement.setString(1, '5');

有没有办法为这样的预处理语句提供命名参数：

ParameterizedStatement statement = connection.parameterizeStatement(
    "select * from something where id = $id;");
statement.setString("id", "5");

在Java中是否存在某种东西？

Answer 1

不在基础JDK中，但这听起来像MyBatis SQL Builder类。

例如，

// Anonymous inner class
public String deletePersonSql() {
  return new SQL() {{
    DELETE_FROM("USER");
    WHERE("ID = ${id}");
  }}.toString();
}

// Builder / Fluent style
public String insertPersonSql() {
  String sql = new SQL()
    .INSERT_INTO("USER");
    .VALUES("ID, FIRST_NAME", "${id}, ${firstName}")
    .VALUES("LAST_NAME", "${lastName}")
    .toString(); 
  return sql;
}

Answer 2

JPA查询可以使用命名参数，例如：

EntityManager em = ...
Query q = em.createQuery("SELECT x FROM Magazine x WHERE x.title = :titleParam and x.price > :priceParam");
q.setParameter("titleParam", "JDJ");
q.setParameter("priceParam", 5.0);
List<Magazine> results = (List<Magazine>) q.getResultList();

用Java命名参数化SQL查询

2 个答案: