Updated Druid_SQL_AST (markdown)

Druid_SQL_AST.md

@@ -9,21 +9,13 @@ package com.alibaba.druid.sql.ast;
 interface SQLObject {}
 interface SQLExpr extends SQLObject {}
 interface SQLStatement extends SQLObject {}
+
+interface SQLTableSource extends SQLObject {}
+class SQLSelect extends SQLObject {}
+class SQLSelectQueryBlock extends SQLObject {}
 ```
 
-## 2.1 常用的SQLStatemment
-最常用的Statement当然是SELECT/UPDATE/DELETE/INSERT，他们分别是
-```java
-package com.alibaba.druid.sql.ast.statement;
-
-class SQLSelectStatement implements SQLStatement {}
-class SQLUpdateStatement implements SQLStatement {}
-class SQLDeleteStatement implements SQLStatement {}
-class SQLInsertStatement implements SQLStatement {}
-```
-
-
-## 2.2 常用的SQLExpr有哪些
+## 2.1 常用的SQLExpr有哪些
 ```java
 package com.alibaba.druid.sql.ast.expr;
 
@@ -33,7 +25,9 @@ class SQLIdentifierExpr implements SQLExpr {}
 // A.ID = 3 这里的A.ID是一个SQLPropertyExpr
 class SQLPropertyExpr implements SQLExpr {} 
 
-// 比如 ID = 3 这是一个SQLBinaryOpExpr，left是ID (SQLIdentifierExpr)，right是3 (SQLIntegerExpr)
+// 比如 ID = 3 这是一个SQLBinaryOpExpr
+// left是ID (SQLIdentifierExpr)
+// right是3 (SQLIntegerExpr)
 class SQLBinaryOpExpr implements SQLExpr {
     SQLExpr left;
     SQLExpr right;
@@ -41,6 +35,31 @@ class SQLBinaryOpExpr implements SQLExpr {
 }
 ```
 
+## 2.2 常用的SQLStatemment
+最常用的Statement当然是SELECT/UPDATE/DELETE/INSERT，他们分别是
+```java
+package com.alibaba.druid.sql.ast.statement;
+
+class SQLSelectStatement implements SQLStatement {
+    SQLSelect select;
+}
+class SQLUpdateStatement implements SQLStatement {
+    SQLExprTableSource tableSource;
+     List<SQLUpdateSetItem> items;
+     SQLExpr where;
+}
+class SQLDeleteStatement implements SQLStatement {
+    SQLTableSource tableSource; 
+    SQLExpr where;
+}
+class SQLInsertStatement implements SQLStatement {
+    SQLExprTableSource tableSource;
+    List<SQLExpr> columns;
+    SQLSelect query;
+}
+```
+
+
 # 3. 怎样产生AST
 
 ## 3.1 通过SQLUtils产生List&lt;SQLStatement&gt;