SQL - USAR SENTENCIA IF PARA SUMAR FILAS DE UNA MISMA COLUMNA EN SQL

DECLARE @largo_yd INT;

DECLARE @suma_yardas DECIMAL(18,2);

SET @suma_yardas = 0.0;

DECLARE the_cursor CURSOR FOR

    SELECT TOP 10

        LARGO_YD

    FROM

        TBL_INV_TELA

    WHERE

        ACTIVO = 1

        AND EN_CORTE = 0

        AND ID_TIPO_TELA = 160

    GROUP BY

        NO_ROLLO,

        ACTIVO,

        LARGO_YD,

        ID_ROLLO,

        PROGRAMADO

    ORDER BY

        FECHA ASC;

OPEN the_cursor;

FETCH NEXT FROM the_cursor INTO @largo_yd;

WHILE (@@FETCH_STATUS = 0) AND (@consumo_telas <= @suma_yardas)

BEGIN

    SET @suma_yardas = @suma_yardas + @largo_yd;

    FETCH NEXT FROM the_cursor INTO @largo_yd;

END;

CLOSE the_cursor;

DEALLOCATE the_cursor;