digoal
2023-09-28
PostgreSQL , PolarDB , duckdb , 语法糖
duckdb增加了很多SQL语法糖, 目标是要让用户可以随心所欲的写SQL.
https://duckdb.org/2023/08/23/even-friendlier-sql.html
Union by name , 自动补齐空缺字段, append数据
Simply replace UNION with UNION BY NAME or UNION ALL with UNION ALL BY NAME.
CREATE TABLE proverbs AS
SELECT
'Revenge is a dish best served cold' AS klingon_proverb
UNION ALL BY NAME
SELECT
'You will be assimilated' AS borg_proverb,
'If winning is not important, why keep score?' AS klingon_proverb;
FROM proverbs;
| klingon_proverb | borg_proverb |
|---|---|
| Revenge is a dish best served cold | NULL |
| If winning is not important, why keep score? | You will be assimilated |
is particularly useful for DuckDB’s multi-file reading capabilities.
https://duckdb.org/docs/data/multiple_files/combining_schemas#union-by-name
