Numeric has several choices, such as plastic, decimal and so on. It's all implemented by cast

Premise: the ID field of table a is of VARCHAR type.

1. Select CAST(ID is an integer) from it.

2.select cast (id is decimal (18, x)) from a-x refers to decimal places. If you want to keep 2 decimal places, it is 2, and if you don't keep decimal places, it is 0.