Solution: Wait for the table to be altered and then issue the DML operation.
解决办法：等这个表被修改，然后发出dml操作。
2
As all rows in the EMPLOYEE table are X-locked by the first transaction, the second application goes into lock wait mode.
由于employee表中的所有行都被第一个事务独占锁定，第二个应用程序进入了锁等待模式。
3
In cases where the fact table is large in volume, millions or even billions of rows, the wait time for what is perceived to be a simple query may take longer than expected.