coalesce()coalesce()

计算表达式列表,并返回第一个非 null(或非空,适用于字符串)表达式。Evaluates a list of expressions and returns the first non-null (or non-empty for string) expression.

coalesce(tolong("not a number"), tolong("42"), 33) == 42

语法Syntax

coalesce(expr_1, expr_2, ...)coalesce(expr_1, expr_2, ...)

参数Arguments

  • expr_i:要计算的标量表达式。expr_i: A scalar expression, to be evaluated.
  • 所有参数的类型必须相同。All arguments must be of the same type.
  • 最多支持 64 个参数。Maximum of 64 arguments is supported.

返回Returns

其值不为 null(或不为空,适用于字符串表达式)的第一个 expr_i 的值。The value of the first expr_i whose value is not null (or not-empty for string expressions).

示例Example

print result=coalesce(tolong("not a number"), tolong("42"), 33)
resultresult
4242