github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/docs/generated/sql/bnf/on_conflict.bnf (about)

     1  on_conflict ::=
     2  	'ON' 'CONFLICT' ( '(' ( ( name ) ( ( ',' name ) )* ) ')' |  ) 'DO' 'UPDATE' 'SET' ( ( ( ( column_name '=' a_expr ) | ( '(' ( ( ( column_name ) ) ( ( ',' ( column_name ) ) )* ) ')' '=' ( '(' select_stmt ')' | ( '(' ')' | '(' ( a_expr | a_expr ',' | a_expr ',' ( ( a_expr ) ( ( ',' a_expr ) )* ) ) ')' ) ) ) ) ) ( ( ',' ( ( column_name '=' a_expr ) | ( '(' ( ( ( column_name ) ) ( ( ',' ( column_name ) ) )* ) ')' '=' ( '(' select_stmt ')' | ( '(' ')' | '(' ( a_expr | a_expr ',' | a_expr ',' ( ( a_expr ) ( ( ',' a_expr ) )* ) ) ')' ) ) ) ) ) )* ) 
     3  	| 'ON' 'CONFLICT' ( '(' ( ( name ) ( ( ',' name ) )* ) ')' |  ) 'DO' 'NOTHING'