[英]JDBC: Query results and add batch into another table
我有一些mySQL表:“ books”,“ task”和“ task_items”。 我正在構建一個REST API(Java),允許用戶使用一些書來創建任務(基本上是編輯字段)。 當用戶創建新任務時,我正在任務表中創建新行,獲取最后的ID,選擇一些書籍並將其全部添加到task_items表中。 像這樣:
餐桌書:
ID TITLE AUTHOR
1 Book A John
2 Book B Doe
表任務
ID NAME DATE
Empty at begining
表task_items
ID TASK_ID BOOK_ID TITLE AUTHOR
Empty at begining
當用戶訪問api / task / newtask時,我正在執行以下操作:
// Creating task and return it's ID, everything works well
conn.setAutoCommit(false);
query = conn.pareStatement(INSERT INTO task VALUES ("New task", NOW()), Statement.RETURN_GENERATED_KEYS);
query.execute();
ResultSet rs = query.getGeneratedKeys();
if (rs.next()) {
taskId = rs.getInt(1);
}
else {
conn.rollback();
return false; // can't create task
}
// Selecting some (or all) books
query = conn.prepareStatement("SELECT * FROM books");
ResultSet rs = query.executeQuery();
if (!rs.isBeforeFirst()) {
conn.rollback();
return false; // no books
}
// There's some books, insert them into task_items with taskId
// TODO
return true;
因此,我必須將SELECT查詢中的resultSet批量插入task_items中,包括taskID(在所有行中都是commom)。 我不知道該怎么做(TODO部分)。 我將不勝感激。
我知道了。 “ TODO”部分應像這樣:
// There's some books, insert them into task_items with taskId
rs = query.executeQuery();
query = conn
.prepareStatement("INSERT INTO task_items"
+ "(TASK_ID, BOOK_ID, TITLE, AUTHOR)"
+ "VALUES"
+ "(?, ?, ?, ?)");
while (rs.next()) {
query.setInt(1, taskId);
query.setInt(2, rs.getInt("ID"));
query.setString(3, rs.getString("TITLE"));
query.setString(4, rs.getString("AUTHOR"));
query.addBatch();
}
System.out.println("executing batch...");
query.executeBatch();
System.out.println("batch executed");
query.close();
...
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