improve join snippets

Author: camilesing

README.md

@@ -25,13 +25,21 @@ example:
 
 ### 1.4 Snippets 
 snippets keywords:
+- create
+- select
+- insert
+- join
+
 #### create
 ![](images/create_snippets.gif)
 #### select 
-![](images/select_snippets.gif)
+![](images/select_snippets_v2.gif)
 #### insert
 ![](images/insert_snippets.gif)
 
+#### join
+![](images/join_snippets.gif)
+
 ### 1.5 Code Format
 Select your FlinkSQL code and press ```Alt+Shift+f```.
 

images/join_snippets.gif

@@ -59,7 +59,7 @@
     "Join": {
         "prefix": "join",
         "body": [
-            "join table_2 FOR SYSTEM_TIME AS OF table_1.proctime as r on table_1.ip = r.ip"
+            "${1|LEFT,RIGHT,INNER|} JOIN ${2:table_name} FOR SYSTEM_TIME AS OF ${3:table_name}.proctime as r on ${4:table_name}.${5:field} = r.${6:field}"
         ]
     }
 }