添加SQL统计功能，统计SQL中所使用的表和字段

git-svn-id: http://code.alibabatech.com/svn/druid/trunk@266 b9813039-fb51-4c41-a8b9-e21c2acb5095

src/test/java/com/alibaba/druid/sql/mysql/bvt/visitor/MySqlSchemaStatVisitorTest_Subquery.java

@@ -0,0 +1,40 @@
+package com.alibaba.druid.sql.mysql.bvt.visitor;
+
+import java.util.List;
+
+import junit.framework.Assert;
+import junit.framework.TestCase;
+
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.dialect.mysql.parser.MySqlStatementParser;
+import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlSchemaStatVisitor;
+import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlSchemaStatVisitor.Column;
+
+public class MySqlSchemaStatVisitorTest_Subquery extends TestCase {
+
+    public void test_0() throws Exception {
+        String sql = "SELECT id2, name2 FROM (select id, name from users limit 10) a";
+
+        MySqlStatementParser parser = new MySqlStatementParser(sql);
+        List<SQLStatement> statementList = parser.parseStatementList();
+        SQLStatement statemen = statementList.get(0);
+
+        Assert.assertEquals(1, statementList.size());
+
+        MySqlSchemaStatVisitor visitor = new MySqlSchemaStatVisitor();
+        statemen.accept(visitor);
+
+        System.out.println(sql);
+        System.out.println("Tables : " + visitor.getTables());
+        System.out.println("fields : " + visitor.getFields());
+
+        Assert.assertEquals(1, visitor.getTables().size());
+        Assert.assertEquals(true, visitor.getTables().containsKey("users"));
+
+        Assert.assertEquals(2, visitor.getFields().size());
+        Assert.assertEquals(true, visitor.getFields().contains(new Column("users", "id")));
+        Assert.assertEquals(true, visitor.getFields().contains(new Column("users", "name")));
+
+    }
+
+}