[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #2627: Like, NotLike expressions work with literal `NULL`

[GitBox <gi...@apache.org>]

alamb commented on code in PR #2627:
URL: https://github.com/apache/arrow-datafusion/pull/2627#discussion_r883505848


##########
datafusion/core/tests/sql/expr.rs:
##########
@@ -1202,6 +1202,36 @@ async fn nested_subquery() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn like_nlike_with_null_lt() {
+    let ctx = SessionContext::new();
+    let sql = "SELECT column1 like NULL from (values('a'), ('b'), (NULL)) as t";

Review Comment:
   Can you also add a test when the arguments are reversed? For example,:
   
   
   ```suggestion
       let sql = "SELECT column1 like NULL as col_null, NULL like column1 as null_col from (values('a'), ('b'), (NULL)) as t";
   ```



##########
datafusion/core/tests/sql/expr.rs:
##########
@@ -1202,6 +1202,36 @@ async fn nested_subquery() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn like_nlike_with_null_lt() {
+    let ctx = SessionContext::new();
+    let sql = "SELECT column1 like NULL from (values('a'), ('b'), (NULL)) as t";
+    let actual = execute_to_batches(&ctx, sql).await;
+    let expected = vec![
+        "+---------------------+",
+        "| t.column1 Like NULL |",
+        "+---------------------+",
+        "|                     |",
+        "|                     |",
+        "|                     |",
+        "+---------------------+",
+    ];
+    assert_batches_eq!(expected, &actual);
+
+    let sql = "SELECT column1 not like NULL from (values('a'), ('b'), (NULL)) as t";

Review Comment:
   ```suggestion
       let sql = "SELECT column1 not like NULL as col_null, NULL not like column as null_col from (values('a'), ('b'), (NULL)) as t";
   ```



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