Question

我有这个查询只选择两个日期之间的差异：

select date_part('day', 'toDate' - 'fromDate') from "Reservation" where "reservationID" = 1;

但是这给了我这个错误：

运营商不是唯一的。无法选择最佳候选运营商。您可能需要添加显式类型转换。

我该如何解决这个问题？

P.S。这就是我创建＆＃34;预订＆＃34;表：

CREATE TABLE "Reservation"
(
  "reservationID" serial NOT NULL,
  "fromDate" timestamp without time zone NOT NULL DEFAULT '-  infinity'::timestamp without time zone,
  "toDate" timestamp without time zone NOT NULL DEFAULT '-infinity'::timestamp without time zone,
  "staffID" integer NOT NULL DEFAULT 0,
  "customerID" integer NOT NULL DEFAULT 0,
  "roomID" integer NOT NULL DEFAULT 0,
  CONSTRAINT "PK_public.Reservation" PRIMARY KEY ("reservationID"),
  CONSTRAINT "FK_public.Reservation_public.Customer_customerID" FOREIGN KEY    ("customerID")
  REFERENCES "Customer" ("customerID") MATCH SIMPLE
  ON UPDATE NO ACTION ON DELETE CASCADE,
  CONSTRAINT "FK_public.Reservation_public.Room_roomID" FOREIGN KEY ("roomID")
  REFERENCES "Room" ("roomID") MATCH SIMPLE
  ON UPDATE NO ACTION ON DELETE CASCADE,
  CONSTRAINT "FK_public.Reservation_public.Staff_staffID" FOREIGN KEY ("staffID")
  REFERENCES "Staff" ("staffID") MATCH SIMPLE
  ON UPDATE NO ACTION ON DELETE CASCADE
)

Answer 1

您无法使用void updateMatrix(double ***mat, int size, double *vec) { // mat is sizeXsize matrix, length of vec is size+1 *mat = (double**)realloc(*mat, (size + 1)*sizeof(double*)); (*mat)[size] = (double*)malloc((size + 1)*sizeof(double)); for(int i = 0; i < size + 1; i++) { (*mat)[size][i] = vec[i]; } for(int i = 0; i < size; i++) { (*mat)[i] = (double*)realloc((*mat)[i], (size + 1)*sizeof(double)); (*mat)[i][size] = vec[i]; } }代替'列名称

运营商并不是唯一的。无法选择最佳候选运营商。您可能需要添加显式类型转换

1 个答案: