doc: show case how to manipulate select items

Signed-off-by: Andreas Reichel <[email protected]>

Author: manticore-projects

src/test/java/net/sf/jsqlparser/test/AssortedFeatureTests.java

@@ -10,10 +10,14 @@
 package net.sf.jsqlparser.test;
 
 import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.expression.Alias;
+import net.sf.jsqlparser.expression.Function;
 import net.sf.jsqlparser.expression.LongValue;
 import net.sf.jsqlparser.expression.StringValue;
 import net.sf.jsqlparser.parser.CCJSqlParserUtil;
 import net.sf.jsqlparser.statement.Statement;
+import net.sf.jsqlparser.statement.select.PlainSelect;
+import net.sf.jsqlparser.statement.select.SelectItem;
 import net.sf.jsqlparser.util.deparser.ExpressionDeParser;
 import net.sf.jsqlparser.util.deparser.SelectDeParser;
 import net.sf.jsqlparser.util.deparser.StatementDeParser;
@@ -61,4 +65,54 @@ public void testIssue1608() throws JSQLParserException {
                 "INSERT INTO example (num, name, address, tel) VALUES (1, 'name', 'test ', '1234-1234')"));
         System.out.println(cleanStatement("DELETE FROM table1 where col=5 and col2=4"));
     }
+
+    @Test
+    void addSelectItemTest() throws JSQLParserException {
+        String provided = "SELECT col1 FROM WHATEVER";
+        String expected = "SELECT col1, Sum(1, 2) AS col2 FROM WHATEVER";
+
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(provided);
+
+        Function f = new Function("Sum", new LongValue(1), new LongValue(2));
+        SelectItem<?> i = new SelectItem<>(f, new Alias("col2", true));
+
+        select
+                .getSelectItems()
+                .add(i);
+
+        TestUtils.assertStatementCanBeDeparsedAs(select, expected);
+    }
+
+    @Test
+    void removeSelectItemTest() throws JSQLParserException {
+        String provided = "SELECT col1, Sum(1, 2) AS col2 FROM WHATEVER";
+        String expected = "SELECT col1 FROM WHATEVER";
+
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(provided);
+
+        select
+                .getSelectItems()
+                .remove(1);
+
+        TestUtils.assertStatementCanBeDeparsedAs(select, expected);
+    }
+
+    @Test
+    void sweapSelectItemTest() throws JSQLParserException {
+        String provided = "SELECT col1 FROM WHATEVER";
+        String expected = "SELECT Sum(1, 2) AS col1 FROM WHATEVER";
+
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(provided);
+
+        Function f = new Function("Sum", new LongValue(1), new LongValue(2));
+        SelectItem<?> i = new SelectItem<>(f, new Alias("col1", true));
+        select
+                .getSelectItems()
+                .remove(0);
+        select
+                .getSelectItems()
+                .add(0, i);
+
+        TestUtils.assertStatementCanBeDeparsedAs(select, expected);
+    }
 }