addJoin introduced

Author: wumpz

README.md

@@ -25,6 +25,8 @@ The generated hierarchy can be navigated using the Visitor Pattern.
 ## Extensions Version 0.8.7
 
 * Startet a simple utility class **SelectUtils** to collect basic **select** modification tools.
+** addExpression adds a new expression to the select list.
+** addJoin adds a new join to the select.
 * Added support for optional " AS " for aliases. 
 
 ```sql

src/main/java/net/sf/jsqlparser/schema/Table.java

@@ -35,11 +35,15 @@ public class Table implements FromItem {
 	private String schemaName;
 	private String name;
 	private Alias alias;
-    private Pivot pivot;
+	private Pivot pivot;
 
 	public Table() {
 	}
 
+	public Table(String name) {
+		this.name = name;
+	}
+
 	public Table(String schemaName, String name) {
 		this.schemaName = schemaName;
 		this.name = name;
@@ -71,7 +75,7 @@ public void setAlias(Alias alias) {
 		this.alias = alias;
 	}
 
-    public String getWholeTableName() {
+	public String getWholeTableName() {
 
 		String tableWholeName = null;
 		if (name == null) {
@@ -97,19 +101,19 @@ public void accept(IntoTableVisitor intoTableVisitor) {
 	}
 
 	@Override
-    public Pivot getPivot() {
-        return pivot;
-    }
+	public Pivot getPivot() {
+		return pivot;
+	}
 
 	@Override
-    public void setPivot(Pivot pivot) {
-        this.pivot = pivot;
-    }
+	public void setPivot(Pivot pivot) {
+		this.pivot = pivot;
+	}
 
-    @Override
+	@Override
 	public String toString() {
-		return getWholeTableName() +
-                ((pivot != null) ? " "+pivot : "") +
-                ((alias != null) ? alias.toString() : "");
+		return getWholeTableName()
+				+ ((pivot != null) ? " " + pivot : "")
+				+ ((alias != null) ? alias.toString() : "");
 	}
 }

src/main/java/net/sf/jsqlparser/util/SelectUtils.java

@@ -21,7 +21,11 @@
  */
 package net.sf.jsqlparser.util;
 
+import java.util.ArrayList;
+import java.util.List;
 import net.sf.jsqlparser.expression.Expression;
+import net.sf.jsqlparser.schema.Table;
+import net.sf.jsqlparser.statement.select.Join;
 import net.sf.jsqlparser.statement.select.PlainSelect;
 import net.sf.jsqlparser.statement.select.Select;
 import net.sf.jsqlparser.statement.select.SelectExpressionItem;
@@ -40,7 +44,8 @@ private SelectUtils() {
 	}
 
 	/**
-	 * Adds an expression to select statements. E.g. a simple column is an expression.
+	 * Adds an expression to select statements. E.g. a simple column is an
+	 * expression.
 	 *
 	 * @param select
 	 * @param expr
@@ -64,4 +69,29 @@ public void visit(WithItem withItem) {
 			}
 		});
 	}
+
+	/**
+	 * Adds a simple join to a select statement. The introduced join is returned for
+	 * more configuration settings on it (e.g. left join, right join).
+	 * @param select
+	 * @param table
+	 * @param onExpression
+	 * @return 
+	 */
+	public static Join addJoin(Select select, final Table table, final Expression onExpression) {
+		if (select.getSelectBody() instanceof PlainSelect) {
+			PlainSelect plainSelect = (PlainSelect) select.getSelectBody();
+			List<Join> joins = plainSelect.getJoins();
+			if (joins == null) {
+				joins = new ArrayList<Join>();
+				plainSelect.setJoins(joins);
+			}
+			Join join = new Join();
+			join.setRightItem(table);
+			join.setOnExpression(onExpression);
+			joins.add(join);
+			return join;
+		}
+		throw new UnsupportedOperationException("Not supported yet.");
+	}
 }

src/test/java/net/sf/jsqlparser/util/SelectUtilsTest.java

@@ -3,8 +3,11 @@
 import net.sf.jsqlparser.JSQLParserException;
 import net.sf.jsqlparser.expression.LongValue;
 import net.sf.jsqlparser.expression.operators.arithmetic.Addition;
+import net.sf.jsqlparser.expression.operators.relational.EqualsTo;
 import net.sf.jsqlparser.parser.CCJSqlParserUtil;
 import net.sf.jsqlparser.schema.Column;
+import net.sf.jsqlparser.schema.Table;
+import net.sf.jsqlparser.statement.select.Join;
 import net.sf.jsqlparser.statement.select.Select;
 import org.junit.After;
 import org.junit.AfterClass;
@@ -54,4 +57,15 @@ public void testAddExpr() throws JSQLParserException {
 
 		assertEquals("SELECT a, b, 5 + 6 FROM mytable", select.toString());
 	}
+	
+	@Test
+	public void testAddJoin() throws JSQLParserException {
+		Select select = (Select)CCJSqlParserUtil.parse("select a from mytable");
+		final EqualsTo equalsTo = new EqualsTo();
+		equalsTo.setLeftExpression(new Column("a"));
+		equalsTo.setRightExpression(new Column("b"));
+		Join addJoin = SelectUtils.addJoin(select, new Table("mytable2"), equalsTo);
+		addJoin.setLeft(true);
+		assertEquals("SELECT a FROM mytable LEFT JOIN mytable2 ON a = b", select.toString());
+	}
 }