分页查询分页问题

src/main/java/com/example/demo/common/domain/BaseQueryDTO.java

@@ -1,6 +1,7 @@
 package com.example.demo.common.domain;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.NotNull;
 import lombok.*;
 import cn.zhxu.bs.bean.DbField;
 import lombok.experimental.Accessors;
@@ -61,4 +62,8 @@ public class BaseQueryDTO implements Serializable {
     @Schema(description = "排序方式")
     private String sortOrder;
 
+    @NotNull(message = "页码不能为空")
+    public int getPageNum() {
+        return (this.pageNum - 1) * pageSize;
+    }
 }