improved sql parser for mysql explain. for issue #1645

src/main/java/com/alibaba/druid/sql/ast/statement/SQLExplainStatement.java

@@ -24,6 +24,8 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLExplainStatement extends SQLStatementImpl {
 
+    private String type;
+
     protected SQLStatement       statement;
 
     private List<SQLCommentHint> hints;
@@ -47,6 +49,14 @@ public class SQLExplainStatement extends SQLStatementImpl {
         this.statement = statement;
     }
 
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
     @Override
     protected void accept0(SQLASTVisitor visitor) {
         if (visitor.visit(this)) {