improved SchemaStatVisitor, TableStatColumn support dataType

src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java

@@ -1291,7 +1291,8 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
         }
 
         String columnName = x.getName().toString();
-        addColumn(tableName, columnName);
+        Column column = addColumn(tableName, columnName);
+        column.setDataType(x.getDataType().getName());
 
         return false;
     }

src/main/java/com/alibaba/druid/stat/TableStat.java

@@ -409,6 +409,11 @@ public class TableStat {
 
         private transient String    fullName;
 
+        /**
+         * @since 1.0.20
+         */
+        private String              dataType;
+
         public Column(){
 
         }
@@ -487,6 +492,20 @@ public class TableStat {
             this.name = name;
             this.fullName = null;
         }
+        
+        /**
+         * @since 1.0.20
+         */
+        public String getDataType() {
+            return dataType;
+        }
+
+        /**
+         * @since 1.0.20
+         */
+        public void setDataType(String dataType) {
+            this.dataType = dataType;
+        }
 
         public Map<String, Object> getAttributes() {
             return attributes;