improve sql parser for sql server

src/test/java/com/alibaba/druid/bvt/pool/PSCacheTest5.java

@@ -0,0 +1,49 @@
+package com.alibaba.druid.bvt.pool;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+
+import org.junit.Assert;
+
+import junit.framework.TestCase;
+
+import com.alibaba.druid.mock.MockPreparedStatement;
+import com.alibaba.druid.pool.DruidDataSource;
+import com.alibaba.druid.util.JdbcUtils;
+
+public class PSCacheTest5 extends TestCase {
+
+    private DruidDataSource dataSource;
+
+    protected void setUp() throws Exception {
+        dataSource = new DruidDataSource();
+        dataSource.setUrl("jdbc:mock:x1");
+        dataSource.setPoolPreparedStatements(true);
+        dataSource.setMaxOpenPreparedStatements(10);
+    }
+
+    protected void tearDown() throws Exception {
+        JdbcUtils.close(dataSource);
+    }
+
+    public void test_0() throws Exception {
+        MockPreparedStatement mockStmt = null;
+        {
+            Connection conn = dataSource.getConnection();
+            PreparedStatement ps = conn.prepareStatement("select 1");
+            mockStmt = ps.unwrap(MockPreparedStatement.class);
+            ps.execute();
+            conn.close();
+        }
+        for (int i = 0; i < 1000; ++i) {
+            Connection conn = dataSource.getConnection();
+            PreparedStatement ps = conn.prepareStatement("select 1");
+            
+            Assert.assertSame(mockStmt, ps.unwrap(MockPreparedStatement.class));
+            
+            ps.execute();
+            ps.close();
+            conn.close();
+        }
+    }
+}