diff --git a/store/db/mysql/memo.go b/store/db/mysql/memo.go
index 5b1b4667..271fe0c9 100644
--- a/store/db/mysql/memo.go
+++ b/store/db/mysql/memo.go
@@ -121,8 +121,11 @@ func (d *DB) ListMemos(ctx context.Context, find *store.FindMemo) ([]*store.Memo
 		if err := d.ConvertExprToSQL(convertCtx, parsedExpr.GetExpr()); err != nil {
 			return nil, err
 		}
-		where = append(where, fmt.Sprintf("(%s)", convertCtx.Buffer.String()))
-		args = append(args, convertCtx.Args...)
+		condition := convertCtx.Buffer.String()
+		if condition != "" {
+			where = append(where, fmt.Sprintf("(%s)", condition))
+			args = append(args, convertCtx.Args...)
+		}
 	}
 	if find.ExcludeComments {
 		having = append(having, "`parent_id` IS NULL")
diff --git a/store/db/postgres/memo.go b/store/db/postgres/memo.go
index 242fe040..104c8a04 100644
--- a/store/db/postgres/memo.go
+++ b/store/db/postgres/memo.go
@@ -113,8 +113,11 @@ func (d *DB) ListMemos(ctx context.Context, find *store.FindMemo) ([]*store.Memo
 		if err := d.ConvertExprToSQL(convertCtx, parsedExpr.GetExpr()); err != nil {
 			return nil, err
 		}
-		where = append(where, fmt.Sprintf("(%s)", convertCtx.Buffer.String()))
-		args = append(args, convertCtx.Args...)
+		condition := convertCtx.Buffer.String()
+		if condition != "" {
+			where = append(where, fmt.Sprintf("(%s)", condition))
+			args = append(args, convertCtx.Args...)
+		}
 	}
 	if find.ExcludeComments {
 		where = append(where, "memo_relation.related_memo_id IS NULL")
diff --git a/store/db/sqlite/memo.go b/store/db/sqlite/memo.go
index d1ea204a..a66d7c00 100644
--- a/store/db/sqlite/memo.go
+++ b/store/db/sqlite/memo.go
@@ -113,8 +113,11 @@ func (d *DB) ListMemos(ctx context.Context, find *store.FindMemo) ([]*store.Memo
 		if err := d.ConvertExprToSQL(convertCtx, parsedExpr.GetExpr()); err != nil {
 			return nil, err
 		}
-		where = append(where, fmt.Sprintf("(%s)", convertCtx.Buffer.String()))
-		args = append(args, convertCtx.Args...)
+		condition := convertCtx.Buffer.String()
+		if condition != "" {
+			where = append(where, fmt.Sprintf("(%s)", condition))
+			args = append(args, convertCtx.Args...)
+		}
 	}
 	if find.ExcludeComments {
 		where = append(where, "`parent_id` IS NULL")
diff --git a/store/db/sqlite/memo_filter_test.go b/store/db/sqlite/memo_filter_test.go
index c78b5d0d..27889ec7 100644
--- a/store/db/sqlite/memo_filter_test.go
+++ b/store/db/sqlite/memo_filter_test.go
@@ -54,6 +54,11 @@ func TestConvertExprToSQL(t *testing.T) {
 			want:   "(JSON_EXTRACT(`memo`.`payload`, '$.tags') LIKE ? OR `memo`.`content` LIKE ?)",
 			args:   []any{`%"tag1"%`, "%hello%"},
 		},
+		{
+			filter: `1`,
+			want:   "",
+			args:   []any{},
+		},
 	}
 
 	for _, tt := range tests {