On join conditions (from, to) we should use Column and not Alias Column.

if we use Alias column on Join Conditions we will have alias used, what will cause an error. We should not have `join b on a.col = b.alias`. b.alias should not be present in the join, it will raise an error. The correct version should be `join b on a.col = b.col`.

Author: uaihebert

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Column.java

@@ -32,6 +32,10 @@ public class Column extends AbstractSegment implements Expression, Named {
 private final SqlIdentifier name;
 private final Table table;
 
+Column(Column column) {
+this(column.name, column.table);
+}
+
 Column(String name, Table table) {
 
 super(table);

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/DefaultSelectBuilder.java

@@ -320,7 +320,7 @@ static class JoinBuilder implements SelectOn, SelectOnConditionComparison, Selec
 @Override
 public SelectOnConditionComparison on(Expression column) {
 
-this.from = column;
+this.from = new Column((Column) column);
 return this;
 }
 
@@ -330,7 +330,7 @@ public SelectOnConditionComparison on(Expression column) {
  */
 @Override
 public JoinBuilder equals(Expression column) {
-this.to = column;
+this.to = new Column((Column) column);
 return this;
 }
 

spring-data-relational/src/test/java/org/springframework/data/relational/core/sql/render/SelectRendererUnitTests.java

@@ -349,4 +349,23 @@ public void shouldRenderWithRenderContext() {
 assertThat(rendered).isEqualTo(
 "SELECT COUNT(\"my_table\".*) AS counter, \"my_table\".\"reserved_keyword\" FROM \"my_table\" JOIN \"join_table\" ON \"my_table\".source = \"join_table\".target");
 }
+
+@Test // DATAJDBC-353
+public void shouldRenderWithColumnAlias() {
+Table a = SQL.table("a").as("a_alias"); Column aColumn = a.column("a_col").as("a_col_alias");
+Table b = SQL.table("b").as("b_alias"); Column bColumn = b.column("a_col").as("b_col_alias");
+
+Select select = Select.builder().select(aColumn, bColumn)
+.from(a)
+.join(b).on(aColumn).equals(bColumn)
+.build();
+
+String target = SqlRenderer.toString(select);
+assertThat(target)
+.isEqualTo(
+"SELECT a_alias.a_col AS a_col_alias, b_alias.a_col AS b_col_alias "
++ "FROM a a_alias "
++ "JOIN b b_alias ON a_alias.a_col = b_alias.a_col"
+);
+}
 }