From 06eaf41c4f9b70e91c7f9bc580eb4f6cab79587a Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@users.noreply.github.com>
Date: Mon, 16 Sep 2024 12:05:37 +0100
Subject: [PATCH] Fix #151.

---
 driver/driver.go     | 28 +++++++++++++++++++++++++++-
 tests/driver_test.go | 14 ++++++++++----
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/driver/driver.go b/driver/driver.go
index c6c758a..25fadca 100644
--- a/driver/driver.go
+++ b/driver/driver.go
@@ -578,6 +578,7 @@ type rows struct {
 	*stmt
 	names []string
 	types []string
+	nulls []bool
 }
 
 func (r *rows) Close() error {
@@ -596,6 +597,22 @@ func (r *rows) Columns() []string {
 	return r.names
 }
 
+func (r *rows) loadTypes() {
+	if r.nulls == nil {
+		count := r.Stmt.ColumnCount()
+		r.nulls = make([]bool, count)
+		r.types = make([]string, count)
+		for i := range r.nulls {
+			if col := r.Stmt.ColumnOriginName(i); col != "" {
+				r.types[i], _, r.nulls[i], _, _, _ = r.Stmt.Conn().TableColumnMetadata(
+					r.Stmt.ColumnDatabaseName(i),
+					r.Stmt.ColumnTableName(i),
+					col)
+			}
+		}
+	}
+}
+
 func (r *rows) declType(index int) string {
 	if r.types == nil {
 		count := r.Stmt.ColumnCount()
@@ -608,7 +625,8 @@ func (r *rows) declType(index int) string {
 }
 
 func (r *rows) ColumnTypeDatabaseTypeName(index int) string {
-	decltype := r.declType(index)
+	r.loadTypes()
+	decltype := r.types[index]
 	if len := len(decltype); len > 0 && decltype[len-1] == ')' {
 		if i := strings.LastIndexByte(decltype, '('); i >= 0 {
 			decltype = decltype[:i]
@@ -617,6 +635,14 @@ func (r *rows) ColumnTypeDatabaseTypeName(index int) string {
 	return strings.TrimSpace(decltype)
 }
 
+func (r *rows) ColumnTypeNullable(index int) (nullable, ok bool) {
+	r.loadTypes()
+	if r.nulls[index] {
+		return false, true
+	}
+	return true, false
+}
+
 func (r *rows) Next(dest []driver.Value) error {
 	old := r.Stmt.Conn().SetInterrupt(r.ctx)
 	defer r.Stmt.Conn().SetInterrupt(old)
diff --git a/tests/driver_test.go b/tests/driver_test.go
index 777159f..54944a0 100644
--- a/tests/driver_test.go
+++ b/tests/driver_test.go
@@ -33,7 +33,7 @@ func TestDriver(t *testing.T) {
 	defer conn.Close()
 
 	res, err := conn.ExecContext(ctx,
-		`CREATE TABLE users (id INT, name VARCHAR(10))`)
+		`CREATE TABLE users (id INTEGER PRIMARY KEY NOT NULL, name VARCHAR(10))`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -82,11 +82,17 @@ func TestDriver(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got := typs[0].DatabaseTypeName(); got != "INT" {
-		t.Errorf("got %s, want INT", got)
+	if got := typs[0].DatabaseTypeName(); got != "INTEGER" {
+		t.Errorf("got %s, want INTEGER", got)
 	}
 	if got := typs[1].DatabaseTypeName(); got != "VARCHAR" {
-		t.Errorf("got %s, want INT", got)
+		t.Errorf("got %s, want VARCHAR", got)
+	}
+	if got, ok := typs[0].Nullable(); got || !ok {
+		t.Errorf("got %v/%v, want false/true", got, ok)
+	}
+	if got, ok := typs[1].Nullable(); !got || ok {
+		t.Errorf("got %v/%v, want true/false", got, ok)
 	}
 
 	row := 0