clickhouse支持udf，通过ambda表达式使用

• UDF
  用户可通过添加lambda表达式，创建自定义Function

  CREATE FUNCTION linear_equation AS (x, k, b) -> k*x + b;
  SELECT number, linear_equation(number, 2, 1) FROM numbers(3);
  
  SELECT
      number,
      linear_equation(number, 2, 1)
  FROM numbers(3)
  
  Query id: 9a4a2978-b186-4bc2-ac0c-86daf0328212
  
  ┌─number─┬─plus(multiply(2, number), 1)─┐
  │      0 │                            1 │
  │      1 │                            3 │
  │      2 │                            5 │
  └────────┴──────────────────────────────┘
  
  3 rows in set. Elapsed: 0.002 sec. 
  
  CREATE FUNCTION parity_str AS (n) -> if(n % 2, 'odd', 'even');
  SELECT number, parity_str(number) FROM numbers(3);
  
  SELECT
      number,
      parity_str(number)
  FROM numbers(3)
  
  Query id: 59a97a32-15c4-4417-8444-51cb00a01ac0
  
  ┌─number─┬─if(modulo(number, 2), 'odd', 'even')─┐
  │      0 │ even                                 │
  │      1 │ odd                                  │
  │      2 │ even                                 │
  └────────┴──────────────────────────────────────┘
  
  3 rows in set. Elapsed: 0.002 sec. 

   

标签：even,parity,number,ambda,udf,clickhouse,odd,SELECT,numbers
来源： https://www.cnblogs.com/MrYang-11-GetKnow/p/15945461.html