Updated Druid_SQL_AST (markdown)

Druid_SQL_AST.md

@@ -163,6 +163,21 @@ class SQLUnionQuery implements SQLSelectQuery {
 }
 ```
 
+## 2.5 SQLCreateTableStatement
+```java
+public class SQLCreateTableStatement extends SQLStatementImpl implements SQLDDLStatement, SQLCreateStatement {
+    SQLExprTableSource tableSource;
+    List<SQLTableElement> tableElementList;
+    Select select;
+
+    // 忽略大小写的查找SQLCreateTableStatement中的SQLColumnDefinition
+    public SQLColumnDefinition findColumn(String columName) {}
+
+    // 忽略大小写的查找SQLCreateTableStatement中的column关联的索引
+    public SQLTableElement findIndex(String columnName);
+}
+```
+
 # 3. 怎样产生AST
 
 ## 3.1. 通过SQLUtils产生List&lt;SQLStatement&gt;