Question

我试图在SAP HANA中创建2个（多个）顶点，如 -

为顶点创建两个表 ITEM 和 DATASET

CREATE COLUMN TABLE "GREEK_MYTHOLOGY"."ITEM" (
"ITEM_ID" VARCHAR(100) PRIMARY KEY,
"ITEM_NAME" VARCHAR(100)
);

CREATE COLUMN TABLE "GREEK_MYTHOLOGY"."DATASET" (
"DATASET_ID" VARCHAR(100) PRIMARY KEY,
"DATASET_NAME" VARCHAR(100)
);

创建优势 REFERENCES

CREATE COLUMN TABLE "GREEK_MYTHOLOGY"."REFERENCES" (
"REF_ID" INT UNIQUE NOT NULL,
"SOURCE" VARCHAR(100) NOT NULL
REFERENCES "GREEK_MYTHOLOGY"."ITEM" ("ITEM_ID")
ON UPDATE CASCADE ON DELETE CASCADE,
"TARGET" VARCHAR(100) NOT NULL
REFERENCES "GREEK_MYTHOLOGY"."DATASET" ("DATASET_ID")
ON UPDATE CASCADE ON DELETE CASCADE,
"TYPE" VARCHAR(100)
);

现在我想将两个顶点（ ITEM 和 DATASET ）连接到边缘参考，如下所示

CREATE GRAPH WORKSPACE "GREEK_MYTHOLOGY"."GRAPH"
EDGE TABLE "GREEK_MYTHOLOGY"."DATASET"
SOURCE COLUMN "SOURCE" 
TARGET COLUMN "TARGET"
VERTEX TABLE "GREEK_MYTHOLOGY"."ITEM" KEY COLUMN "ITEM_ID"
VERTEX TABLE "GREEK_MYTHOLOGY"."DATASET"KEY COLUMN "DATASET_ID"
KEY COLUMN "REF_ID";

但是它会在行

处抛出异常

VERTEX TABLE＆＃34; GREEK_MYTHOLOGY＆＃34;。＆＃34; DATASET＆＃34; KEY COLUMN＆＃34; DATASET_ID＆＃34;

sql syntax error: incorrect syntax near "VERTEX": line 6 col 1 (at pos 200)

是否可以在SAP HANA图中创建多个顶点？如果是，那么正确的方法是什么。

Answer 1

这里存在误解。 REFERENCES语句中的CREATE TABLE子句与您要表示的图结构无关。相反，它在两个表之间定义了外键约束。

CREATE GRAPH WORKSPACE命令只接受一个EDGE TABLE和一个VERTEX TABLE作为参数。不过，您也可以在此处传递同义词或观看次数。

这样，您可以像这样创建一个视图"ALL_ITEMS"：

CREATE VIEW "GREEK_MYTHOLOGY"."ALL_ITEMS" as
  SELECT "ITEM_ID" as "ID", "ITEM_NAME" as "NAME"  FROM "GREEK_MYTHOLOGY"."ITEM"
  UNION 
  SELECT "DATASET_ID" as "ID", "DATASET_NAME" as "NAME" FROM "GREEK_MYTHOLOGY"."DATASET";

然后引用此视图：

CREATE GRAPH WORKSPACE "GREEK_MYTHOLOGY"."GRAPH"
       EDGE TABLE "GREEK_MYTHOLOGY"."DATASET"
            SOURCE COLUMN "SOURCE" 
            TARGET COLUMN "TARGET"
       VERTEX TABLE "GREEK_MYTHOLOGY"."ALL_ITEMS"
            KEY COLUMN "NAME";

使用此方法是可行的，但您现在必须确保"NAME"值在两个表中都是唯一的而不是NULL。

如何在SAP HANA Graph中创建多个顶点

1 个答案: