[ADQL] Fix the SQL translation of concatenations for MySQL and MS-SQLServer.

As @vforchi said:

> The ANSI standard `||` is supported only by Oracle and Postgres: MySQL uses
> `CONCAT` and SQLServer uses `+`.

_This commit resolves the issue #70 ._

src/adql/translator/MySQLTranslator.java

@@ -5,6 +5,8 @@ import adql.db.DBType.DBDatatype;
 import adql.db.STCS.Region;
 import adql.parser.ParseException;
 import adql.query.IdentifierField;
+import adql.query.operand.ADQLOperand;
+import adql.query.operand.Concatenation;
 import adql.query.operand.function.geometry.AreaFunction;
 import adql.query.operand.function.geometry.BoxFunction;
 import adql.query.operand.function.geometry.CentroidFunction;
@@ -34,20 +36,23 @@ import adql.query.operand.function.geometry.RegionFunction;
  * 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 2017 - Astronomisches Rechen Institut (ARI)
+ * Copyright 2017-2019 - Astronomisches Rechen Institut (ARI),
+ *                       UDS/Centre de Données astronomiques de Strasbourg (CDS)
  */
 
 /**
- * <p>Translates all ADQL objects into an SQL interrogation query designed for MySQL.</p>
+ * Translates all ADQL objects into an SQL interrogation query designed for
+ * MySQL.
  *
  * <p><i><b>Important</b>:
  * 	The geometrical functions are translated exactly as in ADQL.
- * 	You will probably need to extend this translator to correctly manage the geometrical functions.
+ * 	You will probably need to extend this translator to correctly manage the
+ * 	geometrical functions.
  * </i></p>
  *
- * @author Gr&eacute;gory Mantelet (ARI)
- * @version 2.1 (08/2017)
- * @since 2.1
+ * @author Gr&eacute;gory Mantelet (ARI;CDS)
+ * @version 1.5 (03/2019)
+ * @since 1.4
  */
 public class MySQLTranslator extends JDBCTranslator {
 
@@ -125,6 +130,28 @@ public class MySQLTranslator extends JDBCTranslator {
 			return str.append(id);
 	}
 
+	/* ********************************************************************** */
+	/* *                                                                    * */
+	/* * GENERAL TRANSLATIONS                                               * */
+	/* *                                                                    * */
+	/* ********************************************************************** */
+
+	@Override
+	public String translate(Concatenation concat) throws TranslationException{
+		StringBuffer translated = new StringBuffer();
+
+		for(ADQLOperand op : concat){
+			if (translated.length() == 0)
+				translated.append("CONCAT(");
+			else
+				translated.append(", ");
+			translated.append(translate(op));
+		}
+		translated.append(")");
+
+		return translated.toString();
+	}
+
 	/* ********************************************************************** */
 	/* *                                                                    * */
 	/* * TYPE MANAGEMENT                                                    * */
@@ -145,7 +172,8 @@ public class MySQLTranslator extends JDBCTranslator {
 		if (params != null && params.length > 0){
 			try{
 				lengthParam = Integer.parseInt(params[0]);
-			}catch(NumberFormatException nfe){}
+			}catch(NumberFormatException nfe){
+			}
 		}
 
 		// SMALLINT

src/adql/translator/SQLServerTranslator.java

 package adql.translator;
 
+/*
+ * This file is part of ADQLLibrary.
+ *
+ * ADQLLibrary is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ADQLLibrary is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * 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 2017-2019 - Astronomisches Rechen Institut (ARI),
+ *                       UDS/Centre de Données astronomiques de Strasbourg (CDS)
+ */
+
 import java.util.Iterator;
 
 import adql.db.DBColumn;
@@ -17,6 +37,8 @@ import adql.query.from.ADQLJoin;
 import adql.query.from.ADQLTable;
 import adql.query.from.FromContent;
 import adql.query.operand.ADQLColumn;
+import adql.query.operand.ADQLOperand;
+import adql.query.operand.Concatenation;
 import adql.query.operand.function.MathFunction;
 import adql.query.operand.function.geometry.AreaFunction;
 import adql.query.operand.function.geometry.BoxFunction;
@@ -32,11 +54,12 @@ import adql.query.operand.function.geometry.PolygonFunction;
 import adql.query.operand.function.geometry.RegionFunction;
 
 /**
- * <p>MS SQL Server translator.</p>
+ * MS SQL Server translator.
  *
  * <p><b>Important:</b>
- * 	This translator works correctly ONLY IF {@link SQLServer_ADQLQueryFactory} has been used
- * 	to create any ADQL query this translator is asked to translate.
+ * 	This translator works correctly ONLY IF {@link SQLServer_ADQLQueryFactory}
+ * 	has been used to create any ADQL query this translator is asked to
+ * 	translate.
  * </p>
  *
  * TODO See how case sensitivity is supported by MS SQL Server and modify this translator accordingly.
@@ -49,11 +72,12 @@ import adql.query.operand.function.geometry.RegionFunction;
  *      {@link #convertTypeToDB(DBType)}).
  *
  * <p><i><b>Important note:</b>
- * 	Geometrical functions are not translated ; the translation returned for them is their ADQL expression.
+ * 	Geometrical functions are not translated ; the translation returned for them
+ * 	is their ADQL expression.
  * </i></p>
  *
- * @author Gr&eacute;gory Mantelet (ARI)
- * @version 1.4 (09/2017)
+ * @author Gr&eacute;gory Mantelet (ARI;CDS)
+ * @version 1.5 (03/2019)
  * @since 1.4
  *
  * @see SQLServer_ADQLQueryFactory
@@ -151,6 +175,19 @@ public class SQLServerTranslator extends JDBCTranslator {
 		return sql;
 	}
 
+	@Override
+	public String translate(Concatenation concat) throws TranslationException{
+		StringBuffer translated = new StringBuffer();
+
+		for(ADQLOperand op : concat){
+			if (translated.length() > 0)
+				translated.append(" + ");
+			translated.append(translate(op));
+		}
+
+		return translated.toString();
+	}
+
 	@Override
 	public String translate(final ADQLJoin join) throws TranslationException{
 		StringBuffer sql = new StringBuffer(translate(join.getLeftTable()));
@@ -361,7 +398,8 @@ public class SQLServerTranslator extends JDBCTranslator {
 		if (params != null && params.length > 0){
 			try{
 				lengthParam = Integer.parseInt(params[0]);
-			}catch(NumberFormatException nfe){}
+			}catch(NumberFormatException nfe){
+			}
 		}
 
 		// SMALLINT

test/adql/translator/TestMySQLTranslator.java

+package adql.translator;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import org.junit.Test;
+
+import adql.parser.ADQLParser;
+import adql.parser.ParseException;
+import adql.query.ADQLQuery;
+
+public class TestMySQLTranslator {
+
+	@Test
+	public void testConcat(){
+		try{
+			MySQLTranslator translator = new MySQLTranslator();
+
+			// Test with an easy translation:
+			ADQLQuery query = (new ADQLParser()).parseQuery("SELECT 'abc' || ' ' || 'def' FROM aTable");
+			assertEquals("SELECT CONCAT('abc', ' ', 'def') AS `concat`", translator.translate(query.getSelect()));
+
+			// Test with an easy translation:
+			query = (new ADQLParser()).parseQuery("SELECT 'a||b||c' || ' ' || 'd+e|f' FROM aTable");
+			assertEquals("SELECT CONCAT('a||b||c', ' ', 'd+e|f') AS `concat`", translator.translate(query.getSelect()));
+
+		}catch(ParseException pe){
+			pe.printStackTrace();
+			fail("The given ADQL query is completely correct. No error should have occurred while parsing it. (see the console for more details)");
+		}catch(TranslationException te){
+			te.printStackTrace();
+			fail("No error was expected from this translation. (see the console for more details)");
+		}
+	}
+
+}

test/adql/translator/TestSQLServerTranslator.java

@@ -83,4 +83,26 @@ public class TestSQLServerTranslator {
 		}
 	}
 
+	@Test
+	public void testConcat(){
+		try{
+			SQLServerTranslator translator = new SQLServerTranslator();
+
+			// Test with an easy translation:
+			ADQLQuery query = (new ADQLParser(new SQLServer_ADQLQueryFactory())).parseQuery("SELECT 'abc' || ' ' || 'def' FROM aTable");
+			assertEquals("SELECT 'abc' + ' ' + 'def' AS \"concat\"", translator.translate(query.getSelect()));
+
+			// Test with an easy translation:
+			query = (new ADQLParser(new SQLServer_ADQLQueryFactory())).parseQuery("SELECT 'a||b||c' || ' ' || 'd+e|f' FROM aTable");
+			assertEquals("SELECT 'a||b||c' + ' ' + 'd+e|f' AS \"concat\"", translator.translate(query.getSelect()));
+
+		}catch(ParseException pe){
+			pe.printStackTrace();
+			fail("The given ADQL query is completely correct. No error should have occurred while parsing it. (see the console for more details)");
+		}catch(TranslationException te){
+			te.printStackTrace();
+			fail("No error was expected from this translation. (see the console for more details)");
+		}
+	}
+
 }