| update_statement ::= UPDATE table_name |
| [ USING update_parameter ( AND update_parameter )* ] |
| SET assignment( ',' assignment )* |
| WHERE where_clause |
| [ IF ( EXISTS | condition ( AND condition)*) ] |
| update_parameter ::= ( TIMESTAMP | TTL ) ( integer | bind_marker ) |
| assignment: simple_selection'=' term |
| `| column_name'=' column_name ( '+' | '-' ) term |
| | column_name'=' list_literal'+' column_name |
| simple_selection ::= column_name |
| | column_name '[' term']' |
| | column_name'.' field_name |
| condition ::= `simple_selection operator term |
