fix(mysql): support IF EXISTS/IF NOT EXISTS revoke/trigger forms

Author: h3n4l

mysql/MySQLParser.g4

@@ -700,7 +700,7 @@ viewSuid:
 ;
 
 createTrigger:
-    definerClause? TRIGGER_SYMBOL triggerName timing = (BEFORE_SYMBOL | AFTER_SYMBOL) event = (
+    definerClause? TRIGGER_SYMBOL ifNotExists? triggerName timing = (BEFORE_SYMBOL | AFTER_SYMBOL) event = (
         INSERT_SYMBOL
         | UPDATE_SYMBOL
         | DELETE_SYMBOL
@@ -1883,15 +1883,19 @@ renameUser:
 ;
 
 revoke:
-    REVOKE_SYMBOL (
+    REVOKE_SYMBOL ifExists? (
         roleOrPrivilegesList FROM_SYMBOL userList
         | roleOrPrivilegesList onTypeTo FROM_SYMBOL userList
         | ALL_SYMBOL PRIVILEGES_SYMBOL? (
             ON_SYMBOL aclType? grantIdentifier
             | COMMA_SYMBOL GRANT_SYMBOL OPTION_SYMBOL FROM_SYMBOL userList
         )
         | PROXY_SYMBOL ON_SYMBOL user FROM_SYMBOL userList
-    )
+    ) ignoreUnknownUser?
+;
+
+ignoreUnknownUser:
+    IGNORE_SYMBOL UNKNOWN_SYMBOL USER_SYMBOL
 ;
 
 onTypeTo: // Optional, starting with 8.0.1.

mysql/examples/create_trigger_if_not_exists.sql

@@ -0,0 +1 @@
+CREATE TRIGGER IF NOT EXISTS `my_trigger` BEFORE INSERT ON `my_table` FOR EACH ROW BEGIN SET NEW.my_col = CONCAT(NEW.mycol, NEW.id); END;

mysql/examples/revoke_if_exists_ignore_unknown_user.sql

@@ -0,0 +1 @@
+REVOKE IF EXISTS Bogus ON test FROM jerry@localhost IGNORE UNKNOWN USER;

mysql/examples/revoke_if_exists_select.sql

@@ -0,0 +1 @@
+REVOKE IF EXISTS SELECT ON test.t1 FROM jerry@localhost;