sql/expression: handle null values in arithmetic expressions

Signed-off-by: Miguel Molina <miguel@erizocosmi.co>
src-d · Jun 21, 2019 · 540082d · 540082d
1 parent 9722f31
commit 540082d
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diff --git a/engine_test.go b/engine_test.go
@@ -1226,6 +1226,10 @@ var queries = []struct {
 		`SELECT CASE i WHEN 1 THEN i ELSE NULL END FROM mytable`,
 		[]sql.Row{{int64(1)}, {nil}, {nil}},
 	},
+	{
+		`SELECT (NULL+1)`,
+		[]sql.Row{{nil}},
+	},
 }
 
 func TestQueries(t *testing.T) {

diff --git a/sql/expression/arithmetic.go b/sql/expression/arithmetic.go
@@ -159,6 +159,10 @@ func (a *Arithmetic) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 		return nil, err
 	}
 
+	if lval == nil || rval == nil {
+		return nil, nil
+	}
+
 	lval, rval, err = a.convertLeftRight(lval, rval)
 	if err != nil {
 		return nil, err