Fix getMetaData error for queries containing TOP (#2287)

Author: lilgreenbird

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerStatement.java

@@ -541,6 +541,11 @@ public String toString() {
     /** Generate the statement's logging ID */
     private static final AtomicInteger lastStatementID = new AtomicInteger(0);
 
+    /*
+     * T-SQL TOP syntax regex
+     */
+    private final static Pattern TOP_SYNTAX = Pattern.compile("\\bTOP\\s*\\(\\s*\\?\\s*\\)", Pattern.CASE_INSENSITIVE);
+
     private static int nextStatementID() {
         return lastStatementID.incrementAndGet();
     }
@@ -1098,6 +1103,11 @@ static String replaceParameterWithString(String str, char marker, String replace
      * @return the result
      */
     static String replaceMarkerWithNull(String sql) {
+        // replace all top(?) to top(1) as null is not valid
+        if (TOP_SYNTAX.matcher(sql).find()) {
+            sql = TOP_SYNTAX.matcher(sql).replaceAll("TOP(1)");
+        }
+
         if (!sql.contains("'")) {
             return replaceParameterWithString(sql, '?', "null");
         } else {

src/test/java/com/microsoft/sqlserver/jdbc/fmtOnly/ParameterMetaDataTest.java

@@ -7,6 +7,7 @@
 import java.sql.Connection;
 import java.sql.ParameterMetaData;
 import java.sql.PreparedStatement;
+import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.Arrays;
@@ -101,7 +102,7 @@ public void exceptionTest() throws SQLException {
     }
 
     @Test
-    public void tempTableTest() throws SQLException {
+    public void getParameterMetaDataTest() throws SQLException {
         String tempTableName = "[#jdbc_temp" + UUID.randomUUID() + "]";
         try (Connection c = PrepUtil.getConnection(AbstractTest.connectionString + ";useFmtOnly=true;");
                 Statement s = c.createStatement()) {
@@ -118,6 +119,29 @@ public void tempTableTest() throws SQLException {
         }
     }
 
+    /**
+     * Tests sql containing TOP
+     * 
+     * @throws SQLException
+     */
+    @Test
+    public void getMetaDataTest() throws SQLException {
+        String tempTableName = "[#jdbc_temp" + UUID.randomUUID() + "]";
+        try (Connection c = PrepUtil.getConnection(AbstractTest.connectionString + ";useFmtOnly=true;");
+                Statement s = c.createStatement(); PreparedStatement p = c
+                        .prepareStatement("SELECT TOP(?) [c1] FROM " + tempTableName + " WHERE c1 = ?")) {
+            TestUtils.dropTableIfExists(tempTableName, s);
+            s.execute("CREATE TABLE " + tempTableName + " (c1 int)");
+
+            ResultSetMetaData rmd = p.getMetaData();
+            assertTrue(rmd.getColumnCount() == 1);
+        } finally {
+            try (Statement s = connection.createStatement()) {
+                TestUtils.dropTableIfExists(tempTableName, s);
+            }
+        }
+    }
+
     @Test
     public void viewTest() throws SQLException {
         String tempViewName = "[jdbc_view" + UUID.randomUUID() + "]";