# 2.9.1
	* fix clean function not clean all fields, #14

# 2.9.0
  * where condition support not nil value, such as `false`, `0` 
  * support tz(timezone) function 

# 2.8.0
  * implement using multiple measurements per select query, #10

# 2.7.0
  * support multi query

# 2.6.3
  * fix grouping by time with offset, #7

# 2.6.2
  * Quote the date string when it includes `\s` or `-`

# 2.6.1
  * Ignore empty condition query, #4

# 2.6.0
  * Support `alias` for query field