返回非空值的數量html
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SELECT COUNT( [ * | <field_key> | /<regular_expression>/ ] ) [INTO_clause] FROM_clause [WHERE_clause] [GROUP_BY_clause] [ORDER_BY_clause] [LIMIT_clause] [OFFSET_clause] [SLIMIT_clause] [SOFFSET_clause]
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SELECT COUNT(DISTINCT( [ * | <field_key> | /<regular_expression>/ ] )) […]
COUNT(field_key) # 返回field_key字段的數目
更多信息見:https://docs.influxdata.com/influxdb/v1.2/query_language/functions/#countexpress