BEGIN
    BEGIN TRY
        INSERT INTO table1 SELECT * FROM Z1;
    END TRY
    BEGIN CATCH
        -- you can do something here if you want
    END CATCH;

    -- IF ABOVE FAILS GO TO NEXT QUERY ANYWAY

    BEGIN TRY
        INSERT INTO table1 SELECT * FROM Z2;
    END TRY
    BEGIN CATCH
        -- you can do something here if you want
    END CATCH;

    -- IF ABOVE FAILS GO TO NEXT QUERY ANYWAY

    BEGIN TRY
        INSERT INTO table1 SELECT * FROM Z3;
    END TRY
    BEGIN CATCH
        -- you can do something here if you want
    END CATCH;
END;