Dandandan commented on a change in pull request #9776:
URL: https://github.com/apache/arrow/pull/9776#discussion_r600001227
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File path: rust/datafusion/tests/sql.rs
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@@ -1940,6 +1940,56 @@ async fn query_without_from() -> Result<()> {
Ok(())
}
+#[tokio::test]
+async fn query_cte() -> Result<()> {
+ // Test for SELECT <expression> without FROM.
+ // Should evaluate expressions in project position.
+ let mut ctx = ExecutionContext::new();
+
+ // simple with
+ let sql = "WITH t AS (SELECT 1) SELECT * FROM t";
+ let actual = execute(&mut ctx, sql).await;
+ let expected = vec![vec!["1"]];
+ assert_eq!(expected, actual);
+
+ // with + union
+ let sql = "WITH t AS (SELECT 1 AS a), u AS (SELECT 2 AS a) SELECT * FROM t
UNION ALL SELECT * FROM u";
+ let actual = execute(&mut ctx, sql).await;
+ let expected = vec![vec!["1"], vec!["2"]];
+ assert_eq!(expected, actual);
+
+ // with + join
+ let sql = "WITH t AS (SELECT 1 AS id1), u AS (SELECT 1 AS id2, 5 as x)
SELECT x FROM t JOIN u ON (id1 = id2)";
+ let actual = execute(&mut ctx, sql).await;
+ let expected = vec![vec!["5"]];
+ assert_eq!(expected, actual);
+
+ // backward reference
+ let sql = "WITH t AS (SELECT 1 AS id1), u AS (SELECT * FROM t) SELECT *
from u";
+ let actual = execute(&mut ctx, sql).await;
+ let expected = vec![vec!["1"]];
+ assert_eq!(expected, actual);
+
+ Ok(())
+}
+
+#[tokio::test]
+async fn query_cte_incorrect() -> Result<()> {
+ let ctx = ExecutionContext::new();
+
+ // self reference
+ let sql = "WITH t AS (SELECT * FROM t) SELECT * from u";
+ let plan = ctx.create_logical_plan(&sql);
+ assert!(plan.is_err());
+
+ // forward referencing
+ let sql = "WITH t AS (SELECT * FROM u), u AS (SELECT 1) SELECT * from u";
+ let plan = ctx.create_logical_plan(&sql);
+ assert!(plan.is_err());
Review comment:
Slightly changed the error message + added tests for this:
error message is now: `Table or CTE with name 'u' not found`.
With some extra code it could detect maybe that it is forward referencing to
provide a better user experience.
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