数据仓库服务 GAUSSDB(DWS)-MERGE INTO:示例

时间:2024-10-21 16:50:40

示例

创建目标表products和源表newproducts,并插入数据:

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CREATE TABLE products
(
product_id INTEGER,
product_name VARCHAR2(60),
category VARCHAR2(60)
);

INSERT INTO products VALUES (1501, 'vivitar 35mm', 'electrncs');
INSERT INTO products VALUES (1502, 'olympus is50', 'electrncs');
INSERT INTO products VALUES (1600, 'play gym', 'toys');
INSERT INTO products VALUES (1601, 'lamaze', 'toys');
INSERT INTO products VALUES (1666, 'harry potter', 'dvd');

CREATE TABLE newproducts
(
product_id INTEGER,
product_name VARCHAR2(60),
category VARCHAR2(60)
);

INSERT INTO newproducts VALUES (1502, 'olympus camera', 'electrncs');
INSERT INTO newproducts VALUES (1601, 'lamaze', 'toys');
INSERT INTO newproducts VALUES (1666, 'harry potter', 'toys');
INSERT INTO newproducts VALUES (1700, 'wait interface', 'books');

进行MERGE INTO操作:

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MERGE INTO products p   
USING newproducts np   
ON (p.product_id = np.product_id)   
WHEN MATCHED THEN  
  UPDATE SET p.product_name = np.product_name, p.category = np.category WHERE p.product_name != 'play gym'  
WHEN NOT MATCHED THEN  
  INSERT VALUES (np.product_id, np.product_name, np.category) WHERE np.category = 'books';

查询更新后的结果:

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SELECT * FROM products ORDER BY product_id;
 product_id |  product_name  | category  
------------+----------------+-----------
       1501 | vivitar 35mm   | electrncs
       1502 | olympus camera | electrncs
       1600 | play gym       | toys
       1601 | lamaze         | toys
       1666 | harry potter   | toys
       1700 | wait interface | books
(6 rows)

删除表:

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DROP TABLE products;
DROP TABLE newproducts;
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