Task: 
  Generate SQL code
Problem: 
  Total sales and count order by channelType.
Tables: 
  - Users( "memberId", "gender" ),
  - Orders( "orderId", "memberId",  "payment", "payTime",  "shopId",  "channelType" )
Hints:
  - Join tables if needed, do not join table if not needed; 
  - Use "_" to concat two words in the output SQL, eg. total_sales.
  - Do not sort result.Output only JSON content, do not add extra text.
Output format: 
  { "SQL": "<SQL>", "dimensions": [<dimensions>], "measures": [<measures>], "explanation_chinese": "<explanation_chinese>" } In your response, capitalize a few words to stress main points. Please limit the number of words with all capital letters to less than 17.
user