feat: adapt postgres (close #740)

model/util.go

@@ -0,0 +1,13 @@
+package model
+
+import (
+	"fmt"
+	"github.com/Xhofe/alist/conf"
+)
+
+func columnName(name string) string {
+	if conf.Conf.Database.Type == "postgres" {
+		return fmt.Sprintf(`"%s"`, name)
+	}
+	return fmt.Sprintf("`%s`", name)
+}