如何创建递增列？

Question

我有带有这些列名称的表。

Province/State
Country/Region
Lat
Long
1/22/20
1/23/20
1/24/20
1/25/20
...
...
3/21/20

我知道要创建前4列，但是我不知道如何创建日期列并将其递增。

如何立即实现如此数量的列？谢谢！

已感染

Dead

已恢复

我创建的对象关系数据模型

问题-：为您的数据库模式提交有效的Oracle脚本。

Answer 1

不要尝试创建每天的列；只需创建一个包含位置，日期和每个统计信息（即受感染，已恢复，已死亡等）列的表，然后如果需要对其进行透视处理，则可以在查询（或任何中间层应用程序，即PHP， Java，.net]，您正在使用它来访问数据库。

类似：

CREATE TABLE Regions(
  id        VARCHAR2(6)
            CONSTRAINT regions__id__pk PRIMARY KEY,
  parent_id VARCHAR2(6)
            CONSTRAINT regions_parent__fk REFERENCES Regions ( id ),
  name      VARCHAR2(50)
            CONSTRAINT regions__name__nn NOT NULL
            CONSTRAINT regions__name__u UNIQUE,
  latitude  NUMBER
            CONSTRAINT regions__lat__nn NOT NULL,
  longitude NUMBER
            CONSTRAINT regions__long__nn NOT NULL,
  CONSTRAINT regions__id__chk CHECK (
       ( parent_id IS     NULL AND REGEXP_LIKE( id, '^[A-Z]{2}$' ) )
    OR ( parent_id IS NOT NULL AND REGEXP_LIKE( id, '^[A-Z]{2}-[A-Z0-9]{1,3}$' ) )
  )
);
COMMENT ON COLUMN Regions.id        IS 'ISO 3166-2 Alpha-2 Country Code or ISO 3166-2 Province Code';
COMMENT ON COLUMN Regions.name      IS 'ISO 3166-2 English Short Name.';
COMMENT ON COLUMN Regions.latitude  IS 'Latitude of the region''s main city.';
COMMENT ON COLUMN Regions.longitude IS 'Longitude of the region''s main city.';

CREATE TABLE Virus_Statistics(
  id        NUMBER(20,0)
            GENERATED ALWAYS AS IDENTITY
            CONSTRAINT virus_statistics__id__pk PRIMARY KEY,
  location  VARCHAR2(6)
            CONSTRAINT virus_statistics__loc__nn NOT NULL
            CONSTRAINT virus_statistics__loc__fk REFERENCES Regions ( id ),
  datetime  DATE
            CONSTRAINT virus_statistics__dt__nn NOT NULL
            CONSTRAINT virus_statistics__dt__chk CHECK ( datetime = TRUNC( datetime ) ),
  infected  NUMBER(10,0),
  recovered NUMBER(10,0),
  dead      NUMBER(10,0),
  CONSTRAINT virus_statistics__loc__dt__u UNIQUE ( location, datetime )
);

然后您可以输入数据。例如，区域为：

INSERT INTO Regions ( id, parent_id, name, latitude, longitude )
SELECT 'TH',    NULL, 'Thailand',          15.00000,  101.00000 FROM DUAL UNION ALL
SELECT 'JP',    NULL, 'Japan',             36.00000,  138.00000 FROM DUAL UNION ALL
SELECT 'SG',    NULL, 'Singapore',          1.28333,  103.83333 FROM DUAL UNION ALL
SELECT 'NP',    NULL, 'Nepal',             28.16667,   84.25000 FROM DUAL UNION ALL
SELECT 'MY',    NULL, 'Malaysia',           2.50000,  112.50000 FROM DUAL UNION ALL
SELECT 'CA',    NULL, 'Canada',            45.42472, - 75.69500 FROM DUAL UNION ALL
SELECT 'CA-BC', 'CA', 'British Columbia',  48.40733, -123.32977 FROM DUAL;

并且数据的前三列将是：

INSERT INTO Virus_Statistics ( location, datetime, infected, recovered, dead )
SELECT 'TH',    DATE '2020-01-22', 2 AS i, 0 AS r, 0 AS d FROM DUAL UNION ALL
SELECT 'TH',    DATE '2020-01-23', 3, 0, 0 FROM DUAL UNION ALL
SELECT 'TH',    DATE '2020-01-24', 5, 0, 0 FROM DUAL UNION ALL
SELECT 'JP',    DATE '2020-01-22', 2, 0, 0 FROM DUAL UNION ALL
SELECT 'JP',    DATE '2020-01-23', 1, 0, 0 FROM DUAL UNION ALL
SELECT 'JP',    DATE '2020-01-24', 2, 0, 0 FROM DUAL UNION ALL
SELECT 'SG',    DATE '2020-01-22', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'SG',    DATE '2020-01-23', 1, 0, 0 FROM DUAL UNION ALL
SELECT 'SG',    DATE '2020-01-24', 3, 0, 0 FROM DUAL UNION ALL
SELECT 'NP',    DATE '2020-01-22', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'NP',    DATE '2020-01-23', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'NP',    DATE '2020-01-24', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'MY',    DATE '2020-01-22', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'MY',    DATE '2020-01-23', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'MY',    DATE '2020-01-24', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'CA-BC', DATE '2020-01-22', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'CA-BC', DATE '2020-01-23', 0, 0, 0 FROM DUAL UNION ALL
SELECT 'CA-BC', DATE '2020-01-24', 0, 0, 0 FROM DUAL;

然后，如果您想将其输出为每天的列数，则使用PIVOT：

SELECT *
FROM   (
  SELECT name,
         latitude,
         longitude,
         datetime,
         infected
  FROM   Virus_Statistics v
         INNER JOIN Regions r
         ON ( r.id = v.location )
)
PIVOT (
  MAX( infected )
  FOR datetime IN (
    DATE '2020-01-22' AS "2020-01-22",
    DATE '2020-01-23' AS "2020-01-23",
    DATE '2020-01-24' AS "2020-01-24"
  )
)

哪个输出：

NAME |纬度|经度| 2020-01-22 | 2020-01-23 | 2020-01-24：--------------- | -------：| ---------：| ---------：| ---------：| ---------：日本| 36 | 138 | 2 | 1 | 2马来西亚| 2.5 | 112.5 | 0 | 0 | 0新加坡| 1.28333 | 103.83333 | 0 | 1 | 3尼泊尔| 28.16667 | 84.25 | 0 | 0 | 0不列颠哥伦比亚| 48.40733 | -123.32977 | 0 | 0 | 0泰国| 15 | 101 | 2 | 3 | 5

db <>小提琴here