Adding a SUM Column to a Query - sql

Question

I'm trying to do a query that returns the information of a purchase bill, but also there's another table that has detail of the bill, but I need to add that total to the other query, but I can't add the column, because it says that I need to have in the group by the same objects that in the select, and I tried it this way, but it says that it returns more than one value. Help please! :D
SELECT fc.fecha_factura_compra AS fecha, fc.id_factura AS no_factura, fc.serie,
o.abreviatura + CAST(p.corr_id AS VARCHAR(255)) AS codigo_trupp,
p.nombre, fc.dias_credito, fc.tipo_cambio,
(SELECT SUM(dc.peso_neto * dc.precio_unitario)
FROM detalle_compra AS dc
GROUP BY dc.id_proveedor,
dc.id_factura,
dc.serie) AS total
FROM factura_compra AS fc,
origen AS o,
proveedor AS p,
detalle_compra AS dc
WHERE fc.id_proveedor = p.id_proveedor
AND dc.id_proveedor = p.id_proveedor
AND dc.id_factura = fc.id_factura
AND p.id_origen = o.id_origen
AND dc.serie = fc.serie
AND dc.id_factura = fc.id_factura
AND dc.id_proveedor = fc.id_proveedor
AND fc.activo_inactivo = 'true'
AND fc.anulada = 'false'

Answer 1

The construction with the subquery is extremely slow and to be avoided. A better solution is to write the query like below.
To add a total to a query you need to group by over all the other fields in your result set.
SELECT fc.fecha_factura_compra AS fecha
, fc.id_factura AS no_factura
, fc.serie
, o.abreviatura + CAST(p.corr_id AS VARCHAR(255)) AS codigo_trupp
, p.nombre
, fc.dias_credito
, fc.tipo_cambio
, SUM(dc.peso_neto * dc.precio_unitario) AS total
FROM factura_compra AS fc
JOIN proveedor AS p
ON fc.id_proveedor = p.id_proveedor
JOIN origen AS o
ON p.id_origen = o.id_origen
JOIN detalle_compra AS dc
ON dc.id_factura = fc.id_factura
AND dc.serie = fc.serie
AND dc.id_factura = fc.id_factura
AND dc.id_proveedor = fc.id_proveedor
AND dc.id_proveedor = p.id_proveedor
WHERE fc.activo_inactivo = 'true'
AND fc.anulada = 'false'
GROUP BY fc.fecha_factura_compra
, fc.id_factura
, fc.serie
, o.abreviatura + CAST(p.corr_id AS VARCHAR(255))
, p.nombre
, fc.dias_credito
, fc.tipo_cambio

Answer 2

Instead of grouping by the columns, you should restrict the sub-select on the join columns and omit detalle_compra from the outer select:
SELECT fc.fecha_factura_compra as fecha,
fc.id_factura as no_factura,
fc.serie,
o.abreviatura+CAST(p.corr_id as varchar(255)) as Codigo_Trupp,
p.nombre,
fc.dias_credito,
fc.tipo_cambio,
(select sum(peso_neto*precio_unitario)
from detalle_compra
where serie = fc.serie and
id_factura = fc.id_factura and
id_proveedor = fc.id_proveedor) as Total
FROM factura_compra as fc,origen as o, proveedor as p
WHERE fc.id_proveedor = p.id_proveedor and
p.id_origen = o.id_origen and
fc.activo_inactivo = 'true' and
fc.anulada = 'false'
Side note: Use the BIT type to store booleans:
...
fc.activo_inactivo = 1 and
fc.anulada = 0