EXEC SQL [AT { dbname | :host_variable }]
 [FOR { :host_integer | integer }]
UPDATE
 [ (subquery)
 | [schema .] { table | view } [ @db_link | PARTITION (part_name) ]
 ]
SET
 { column = { expr | (subquery_2) } 
 | (column [, column]...) = (subquery_1)
 } 
 [, { column = { expr | (subquery_2) } 
    | (column [, column]...) = (subquery_1)
    }
 ]...
 [WHERE { condition | CURRENT OF cursor }]  
 [DML.RETURNING.CLAUSE]