更新并返回：无法检索ResultSet

Question

我是不是漏掉了什么？

PreparedStatement statement = this.prepareStatement(
    "WITH temp AS (" +
    "    SELECT id" +
    "    FROM mytable " +
    "    LIMIT 5 "
    ") " +
    "UPDATE mytable " +
    "SET updated = NOW() " +
    "FROM temp " +
    "WHERE temp.id = mytable.id " +
    "RETURNING mytable.data"
);

boolean hasResult = statement.execute();

if (!hasResult) {
    hasResult = statement.getMoreResults();
    // hasResult is still false
    // statement.getResultSet() still returns null
} else {
    // statement.getUpdateCount() returns the correct count of updated rows
}

Answer 1

execute()的返回代码指示是否有立即可用的结果。

getMoreResults()告诉您，在处理通过execute()返回值指示的第一个结果集之后，是否还有其他结果集。

因此，以下内容将与UPDATE语句一起使用：

boolean hasResult = statement.execute();
if (hasResult) {
  ResultSet rs = statement.getResultSet();
  ... process the result ...
}

boolean hasResult = statement.execute();
while (hasResult) {
  ResultSet rs = statement.getResultSet();
  .... process the result ...

  // check if there is another one
  hasResult = statement.getMoreResults();
}