[CALCITE-1866] JDBC adapter generates incorrect code when pushing FLO…

…OR to MySQL (Kang Wang, Sergey Nuyanzin)

Fix format string. DateTime FLOOR to HOUR cause MySQL use '%H' rather than '%k'. (Kang Wang)

Add test-cases for MySQL (FLOOR to HOUR, FLOOR to MINUTE, FLOOR to SECOND) (Sergey Nuyanzin)

Close apache#745

core/src/main/java/org/apache/calcite/sql/dialect/MysqlSqlDialect.java

@@ -193,13 +193,13 @@ private void unparseFloor(SqlWriter writer, SqlCall call) {
       format = "%Y-%m-%d";
       break;
     case HOUR:
-      format = "%Y-%m-%d %k:00:00";
+      format = "%Y-%m-%d %H:00:00";
       break;
     case MINUTE:
-      format = "%Y-%m-%d %k:%i:00";
+      format = "%Y-%m-%d %H:%i:00";
       break;
     case SECOND:
-      format = "%Y-%m-%d %k:%i:%s";
+      format = "%Y-%m-%d %H:%i:%s";
       break;
     default:
       throw new AssertionError("MYSQL does not support FLOOR for time unit: "

core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java

@@ -1286,6 +1286,33 @@ private void checkLiteral2(String expression, String expected) {
         .ok(expected);
   }
 
+  @Test public void testFloorMysqlHour() {
+    String query = "SELECT floor(\"hire_date\" TO HOUR) FROM \"employee\"";
+    String expected = "SELECT DATE_FORMAT(`hire_date`, '%Y-%m-%d %H:00:00')\n"
+        + "FROM `foodmart`.`employee`";
+    sql(query)
+        .withMysql()
+        .ok(expected);
+  }
+
+  @Test public void testFloorMysqlMinute() {
+    String query = "SELECT floor(\"hire_date\" TO MINUTE) FROM \"employee\"";
+    String expected = "SELECT DATE_FORMAT(`hire_date`, '%Y-%m-%d %H:%i:00')\n"
+        + "FROM `foodmart`.`employee`";
+    sql(query)
+        .withMysql()
+        .ok(expected);
+  }
+
+  @Test public void testFloorMysqlSecond() {
+    String query = "SELECT floor(\"hire_date\" TO SECOND) FROM \"employee\"";
+    String expected = "SELECT DATE_FORMAT(`hire_date`, '%Y-%m-%d %H:%i:%s')\n"
+        + "FROM `foodmart`.`employee`";
+    sql(query)
+        .withMysql()
+        .ok(expected);
+  }
+
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-1826">[CALCITE-1826]
    * JDBC dialect-specific FLOOR fails when in GROUP BY</a>. */
@@ -1303,9 +1330,9 @@ private void checkLiteral2(String expression, String expected) {
         + "FROM \"foodmart\".\"employee\"\n"
         + "GROUP BY DATE_TRUNC('MINUTE', \"hire_date\")";
     final String expectedMysql = "SELECT"
-        + " DATE_FORMAT(`hire_date`, '%Y-%m-%d %k:%i:00')\n"
+        + " DATE_FORMAT(`hire_date`, '%Y-%m-%d %H:%i:00')\n"
         + "FROM `foodmart`.`employee`\n"
-        + "GROUP BY DATE_FORMAT(`hire_date`, '%Y-%m-%d %k:%i:00')";
+        + "GROUP BY DATE_FORMAT(`hire_date`, '%Y-%m-%d %H:%i:00')";
     sql(query)
         .withHsqldb()
         .ok(expected)