sqldb: add SQLStrValid helper

The SQL* helpers are meant to always set the `Valid` field of the
sql.Null* type to true. Otherwise they cannot be used to set a valid,
empty field. However, we dont want to break the behaviour of the
existing SQLStr helper and so this commit adds a new helper with the
desired functionality.

sqldb/sqlutils.go

@@ -49,6 +49,10 @@ func SQLInt64[T constraints.Integer](num T) sql.NullInt64 {
 
 // SQLStr turns a string into the NullString that sql/sqlc uses when a string
 // can be permitted to be NULL.
+//
+// NOTE: If the input string is empty, it returns a NullString with Valid set to
+// false. If this is not the desired behavior, consider using SQLStrValid
+// instead.
 func SQLStr(s string) sql.NullString {
 	if s == "" {
 		return sql.NullString{}
@@ -60,6 +64,17 @@ func SQLStr(s string) sql.NullString {
 	}
 }
 
+// SQLStrValid turns a string into the NullString that sql/sqlc uses when a
+// string can be permitted to be NULL.
+//
+// NOTE: Valid is always set to true, even if the input string is empty.
+func SQLStrValid(s string) sql.NullString {
+	return sql.NullString{
+		String: s,
+		Valid:  true,
+	}
+}
+
 // SQLTime turns a time.Time into the NullTime that sql/sqlc uses when a time
 // can be permitted to be NULL.
 func SQLTime(t time.Time) sql.NullTime {