feat: add isnull function

src/common/function/src/scalars/expression/is_null.rs

@@ -30,7 +30,7 @@ use crate::function::{Function, FunctionContext};
 
 const NAME: &str = "isnull";
 
-/// The function to find remainders
+/// The function to check whether an expression is NULL
 #[derive(Clone, Debug, Default)]
 pub struct IsNullFunction;
 

tests/cases/standalone/common/function/expression.result

@@ -1,47 +1,78 @@
+CREATE TABLE t(a INTEGER, ts timestamp time index);
+
+Affected Rows: 0
+
+INSERT INTO t VALUES (1, 1);
+
+Affected Rows: 1
+
+INSERT INTO t VALUES (null, 2);
+
+Affected Rows: 1
+
+INSERT INTO t VALUES (3, 3);
+
+Affected Rows: 1
+
+SELECT ISNULL(a) from t;
+
++-------------+
+| isnull(t.a) |
++-------------+
+| false       |
+| true        |
+| false       |
++-------------+
+
 SELECT ISNULL(null);
 
-+-------------------------+
-| isnull(NULL)            |
-+-------------------------+
-| true                    |
-+-------------------------+
++--------------+
+| isnull(NULL) |
++--------------+
+| true         |
++--------------+
 
 SELECT ISNULL(1);
 
-+-------------------------+
-| isnull(1)               |
-+-------------------------+
-| false                   |
-+-------------------------+
++------------------+
+| isnull(Int64(1)) |
++------------------+
+| false            |
++------------------+
 
 SELECT ISNULL(-1);
 
-+-------------------------+
-| isnull(-1)              |
-+-------------------------+
-| false                   |
-+-------------------------+
++-------------------+
+| isnull(Int64(-1)) |
++-------------------+
+| false             |
++-------------------+
 
 SELECT ISNULL(1.0);
 
-+-------------------------+
-| isnull(1.0)             |
-+-------------------------+
-| false                   |
-+-------------------------+
++--------------------+
+| isnull(Float64(1)) |
++--------------------+
+| false              |
++--------------------+
 
 SELECT ISNULL(true);
 
-+-------------------------+
-| isnull(true)            |
-+-------------------------+
-| false                   |
-+-------------------------+
++-----------------------+
+| isnull(Boolean(true)) |
++-----------------------+
+| false                 |
++-----------------------+
 
 SELECT ISNULL('string');
 
-+-------------------------+
-| isnull(Utf8("string"))  |
-+-------------------------+
-| false                   |
-+-------------------------+
++------------------------+
+| isnull(Utf8("string")) |
++------------------------+
+| false                  |
++------------------------+
+
+DROP TABLE t;
+
+Affected Rows: 0
+

tests/cases/standalone/common/function/expression.sql

@@ -1,3 +1,13 @@
+CREATE TABLE t(a INTEGER, ts timestamp time index);
+
+INSERT INTO t VALUES (1, 1);
+
+INSERT INTO t VALUES (null, 2);
+
+INSERT INTO t VALUES (3, 3);
+
+SELECT ISNULL(a) from t;
+
 SELECT ISNULL(null);
 
 SELECT ISNULL(1);
@@ -8,4 +18,6 @@ SELECT ISNULL(1.0);
 
 SELECT ISNULL(true);
 
-SELECT ISNULL('string');
+SELECT ISNULL('string');
+
+DROP TABLE t;