Repository: gluesql/gluesql (rust)

Issue:
SELECT 1 FROM Test; not working
```sql
SELECT 1 + 1 FROM Test;
```
Above works, but...

```sql
SELECT 1 FROM Test;
```
This doesn't work with this error `[Blend Error] "FieldDefinitionNotSupported"`


Pull request description:
Eval num 
resolve #42 


Patch:
diff --git a/Cargo.toml b/Cargo.toml
index fcaed416..68cf633b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "gluesql"
-version = "0.1.13"
+version = "0.1.15"
 authors = ["Taehoon Moon <panarch@kaist.ac.kr>"]
 edition = "2018"
 description = "GlueSQL - Open source SQL database engine fully written in Rust with pure functional execution layer, easily swappable storage and web assembly support!"
diff --git a/src/executor/blend.rs b/src/executor/blend.rs
index e29125cf..56bba816 100644
--- a/src/executor/blend.rs
+++ b/src/executor/blend.rs
@@ -188,6 +188,11 @@ impl<'a, T: 'static + Debug> Blend<'a, T> {
 
                         Blended::Single(once(value))
                     }
+                    Expr::Value(literal) => {
+                        let value = Value::try_from(literal).map(Rc::new);
+
+                        Blended::Single(once(value))
+                    }
                     _ => err!(BlendError::FieldDefinitionNotSupported),
                 },
                 _ => err!(BlendError::FieldDefinitionNotSupported),


Test patch:
diff --git a/src/tests/blend.rs b/src/tests/blend.rs
index e446aa2a..9cb48b55 100644
--- a/src/tests/blend.rs
+++ b/src/tests/blend.rs
@@ -43,6 +43,7 @@ pub fn blend(mut tester: impl tests::Tester) {
     let mut run = |sql| tester.run(sql).expect("select");
 
     let test_cases = vec![
+        ("SELECT 1 FROM BlendUser", select!(I64; 1; 1; 1)),
         (
             "SELECT id, name FROM BlendUser",
             select!(