[ADQL] Fix return type of some math. functions for MS-SQLServer.

In MS-SQLServer, the following functions return a value of the same
type as the given argument:
  - abs
  - ceiling
  - degrees
  - floor
  - radians
  - round.

Since ADQL requires that these functions return a DOUBLE
(i.e. a float in MS-SQLServer), it must be ensured that the given
argument is a float.

This commit partially fixes the Pull Request #16

src/adql/translator/SQLServerTranslator.java

@@ -16,12 +16,21 @@ package adql.translator;
  * You should have received a copy of the GNU Lesser General Public License
  * along with ADQLLibrary.  If not, see <http://www.gnu.org/licenses/>.
  * 
- * Copyright 2016 - Astronomisches Rechen Institut (ARI)
+ * Copyright 2016-2017 - Astronomisches Rechen Institut (ARI)
  */
 
-import adql.db.*;
+import java.util.ArrayList;
+import java.util.Iterator;
+
+import adql.db.DBChecker;
+import adql.db.DBColumn;
+import adql.db.DBTable;
+import adql.db.DBType;
 import adql.db.DBType.DBDatatype;
+import adql.db.DefaultDBColumn;
+import adql.db.DefaultDBTable;
 import adql.db.STCS.Region;
+import adql.db.SearchColumnList;
 import adql.db.exception.UnresolvedJoinException;
 import adql.parser.ADQLParser;
 import adql.parser.ParseException;
@@ -32,10 +41,18 @@ import adql.query.IdentifierField;
 import adql.query.from.ADQLJoin;
 import adql.query.operand.ADQLColumn;
 import adql.query.operand.function.MathFunction;
-import adql.query.operand.function.geometry.*;
-
-import java.util.ArrayList;
-import java.util.Iterator;
+import adql.query.operand.function.geometry.AreaFunction;
+import adql.query.operand.function.geometry.BoxFunction;
+import adql.query.operand.function.geometry.CentroidFunction;
+import adql.query.operand.function.geometry.CircleFunction;
+import adql.query.operand.function.geometry.ContainsFunction;
+import adql.query.operand.function.geometry.DistanceFunction;
+import adql.query.operand.function.geometry.ExtractCoord;
+import adql.query.operand.function.geometry.ExtractCoordSys;
+import adql.query.operand.function.geometry.IntersectsFunction;
+import adql.query.operand.function.geometry.PointFunction;
+import adql.query.operand.function.geometry.PolygonFunction;
+import adql.query.operand.function.geometry.RegionFunction;
 
 /**
  * <p>MS SQL Server translator.</p>
@@ -59,7 +76,7 @@ import java.util.Iterator;
  * </i></p>
  * 
  * @author Gr&eacute;gory Mantelet (ARI)
- * @version 1.4 (03/2016)
+ * @version 1.4 (09/2017)
  * @since 1.4
  * 
  * @see SQLServer_ADQLQueryFactory
@@ -137,9 +154,12 @@ public class SQLServerTranslator extends JDBCTranslator {
 		return field == null ? false : field.isCaseSensitive(caseSensitivity);
 	}
 
-	/* For SQL Server, translate(ADQLQuery) must be overridden for TOP/LIMIT handling.
-	 * We must not add "LIMIT" at the end of the query, it must go in select.
-	 * @see adql.translator.ADQLTranslator#translate(adql.query.ADQLQuery)
+	/**
+	 * For SQL Server, {@link #translate(ClauseSelect)} must be overridden for
+	 * TOP/LIMIT handling. We must not add the LIMIT at the end of the query, it
+	 * must go in the SELECT.
+	 * 
+	 * @see #translate(ClauseSelect)
 	 */
 	@Override
 	public String translate(ADQLQuery query) throws TranslationException{
@@ -162,10 +182,6 @@ public class SQLServerTranslator extends JDBCTranslator {
 		return sql.toString();
 	}
 
-	/* For SQL Server, translate(ClauseSelect) must be overridden for TOP/LIMIT handling.
-	 * We must not add "LIMIT" at the end of the query, it must go in select.
-	 * @see adql.translator.ADQLTranslator#translate(adql.query.ClauseSelect)
-	 */
 	@Override
 	public String translate(ClauseSelect clause) throws TranslationException{
 		String sql = null;
@@ -323,11 +339,30 @@ public class SQLServerTranslator extends JDBCTranslator {
 		switch(fct.getType()){
 			case TRUNCATE:
 				// third argument to round nonzero means do a truncate
-				return "round(" + ((fct.getNbParameters() >= 2) ? (translate(fct.getParameter(0)) + ", " + translate(fct.getParameter(1))) : "") + ",1)";
+				return "round(convert(float, " + ((fct.getNbParameters() >= 2) ? (translate(fct.getParameter(0)) + ", " + translate(fct.getParameter(1))) : "") + "),1)";
 			case MOD:
-				return ((fct.getNbParameters() >= 2) ? (translate(fct.getParameter(0)) + "% " + translate(fct.getParameter(1))) : "");
+				return ((fct.getNbParameters() >= 2) ? ("convert(float, " + translate(fct.getParameter(0)) + ") % convert(float, " + translate(fct.getParameter(1)) + ")") : "");
 			case ATAN2:
 				return "ATN2(" + translate(fct.getParameter(0)) + ", " + translate(fct.getParameter(1)) + ")";
+
+			/* In MS-SQLServer, the following functions returns a value of the
+			 * same type as the given argument. However, ADQL requires that an
+			 * SQLServer float (so a double in ADQL) is returned. So, in order
+			 * to follow the ADQL standard, the given parameter must be
+			 * converted into a float: */
+			case ABS:
+				return "abs(convert(float, " + translate(fct.getParameter(0)) + "))";
+			case CEILING:
+				return "ceiling(convert(float, " + translate(fct.getParameter(0)) + "))";
+			case DEGREES:
+				return "degrees(convert(float, " + translate(fct.getParameter(0)) + "))";
+			case FLOOR:
+				return "floor(convert(float, " + translate(fct.getParameter(0)) + "))";
+			case RADIANS:
+				return "radians(convert(float, " + translate(fct.getParameter(0)) + "))";
+			case ROUND:
+				return "round(convert(float, " + translate(fct.getParameter(0)) + ")" + ", " + translate(fct.getParameter(1)) + ")";
+
 			default:
 				return getDefaultADQLFunction(fct);
 		}