i have a sql query, but i have problem with this, i would like that the sql query show me all the information in both table that i have...
And it works, but when i put a condition in the sentence, i can't have the full info...
With this query, i can see all information of my table, even if i don't have info in some columns... And i need that, but i want to add a condition, and when i add the condition i can't see all.
Result:
Query without condition
SELECT dbo.tblHoras.IdHora, dbo.tblHoras.Hora, dbo.tblHoras.Meta, COUNT(dbo.tblProductos.Serial) as Cantidad
FROM tblHoras full join
tblProductos
ON tblHoras.IdHora = tblProductos.IdHora
GROUP By tblHoras.IdHora, tblHoras.Hora, tblHoras.Meta
ORDER By tblHoras.IdHora;
And this is the query with the condition, and this doesn't bring me all the info.
SELECT dbo.tblHoras.IdHora, dbo.tblHoras.Hora, dbo.tblHoras.Meta, COUNT(dbo.tblProductos.Serial) as Cantidad
FROM tblHoras full join
tblProductos
ON tblHoras.IdHora = tblProductos.IdHora
WHERE tblProductos.ActualFecha = '2017-04-19'
GROUP By tblHoras.IdHora, tblHoras.Hora, tblHoras.Meta
ORDER By tblHoras.IdHora;
Result:
Query with condition
Based on the fact that you are aggregating only by columns in tblHoras, I think you want a LEFT JOIN:
SELECT h.IdHora, h.Hora, h.Meta, COUNT(p.Serial) as Cantidad
FROM tblHoras h LEFT JOIN
tblProductos p
ON p.IdHora = p.IdHora AND p.ActualFecha = '2017-04-19'
GROUP By h.IdHora, h.Hora, h.Meta
ORDER By h.IdHora;
The filtering condition should then be in the ON clause.
Notice that I also introduced table aliases which make the query easier to write and to read.
Related
I need help making the following query only display one result, the one with the MAX Procurement Rate.
Currently the query works, but displays all results not just the one with the output of the MAX function
SELECT SalesPeople.SalesPersonID, FirstName, LastName, Region, SalesRevenueYear1, ProcurementCost
FROM ProductRevenueAndCosts
INNER JOIN SalesPeople
ON ProductRevenueAndCosts.SalesPersonID = SalesPeople.SalesPersonID
WHERE SalesPeople.Region = 'Central' AND (
SELECT MAX (ProcurementCost)
FROM ProductRevenueAndCosts
WHERE SalesPeople.Region = 'Central'
)
If you add a LIMIT 1 clause at the end of your SQL, then only the first record will be shown. If you add an ORDER BY column_name, then the results will be ordered by that column. Using these two together is a quick way to get the max or min without having to worry about aggregate functions.
https://www.w3schools.com/mysql/mysql_limit.asp
Otherwise, you can try aggregating the results with a max function:
https://www.w3schools.com/mysql/mysql_min_max.asp
As mentioned, you need to correlate the subquery to outer query. Be sure to use aliases between same named columns and exercise good practice in qualifying all columns with table names or aliases especially in JOIN queries:
SELECT sp.SalesPersonID, sp.FirstName, sp.LastName, sp.Region, sp.SalesRevenueYear1,
prc.ProcurementCost
FROM ProductRevenueAndCosts prc
INNER JOIN SalesPeople sp
ON prc.SalesPersonID = prc.SalesPersonID
WHERE sp.Region = 'Central'
AND prc.ProcurementCost = ( -- CORRELATE OUTER QUERY WITH SUBQUERY
SELECT MAX(ProcurementCost)
FROM ProductRevenueAndCosts
)
Note: If running in MS Access, remove the comment
I wanted to ask about the condition of an ON clause while joining tables:
SELECT c_User.ID
FROM c_User
WHERE EXISTS (
SELECT *
FROM c_Group
JOIN c_Member ON (c_Group.Group_Name LIKE 'mcp%')
WHERE
c_Group.Name = c_Member.Parent_Name
AND c_Member.Child_Name = c_User.Lower_User_Name
)
I know that tables c_Member and c_Group have one column with the same name, Directory_ID. What I expected was c_Member and c_Group to join on that column using something like:
c_Group JOIN c_Member ON (c_Group.Directory_ID = c_Member.Directory_ID)
WHERE c_Group.Group_Name like 'mcp%'
How is this condition able to match the rows?
c_Member ON (c_Group.Group_Name LIKE 'mcp%')
Is this is a shorter way of referring to two tables joining on a column with the same name, while applying the LIKE condition?
If so, then can such a style work for a table with multiple column names that are the same?
This is your correlated subquery:
SELECT *
FROM c_Group
JOIN c_Member ON (c_Group.Group_Name LIKE 'mcp%')
WHERE
c_Group.Name = c_Member.Parent_Name
AND c_Member.Child_Name = c_User.Lower_User_Name
This subquery works, but the way it is spelled makes it quite unclear:
The join condition (c_Group.Group_Name LIKE 'mcp%') is not actually not related to the table being joined (c_Member) ; what it actually does is apply filter on table c_Group that makes it filter on (there is no magic such as shorter way of referring to two tables joining on a column with the same name, while applying the LIKE condition). It would make more sense to move it to the WHERE clause (this would still be functionaly equivalent).
On the other hand, the WHERE clause contains conditions that relate to the tables being joined (for example: c_Group.Name = c_Member.Parent_Name). A more sensible option would be to put them in the ON clause of the JOIN.
Other remarks:
when using NOT EXISTS, you usually would prefer SELECT 1 instead of SELECT *, (most RDBMS will optimize this under the hood for you, but this makes the intent clearer).
table aliases can be used to make the query more readable
I would suggest the following syntax for the query (which is basically syntaxically equivalent to the original, but a lot clearer):
SELECT u.ID
FROM c_User u
WHERE EXISTS (
SELECT 1
FROM c_Group g
JOIN c_Member m ON g.Name = m.Parent_Name AND m.Child_Name = u.Lower_User_Name
WHERE g.Group_Name LIKE 'mcp%'
)
The below query returns around 200000 results.
The working of nested where clause in this query is not very clear i.e where is it coming in the picture ?
If I comment out the where clause inside the isNull then I get 0 results, which is fine and expected as the Max(invoiceID) is not null after join.
select * from CustomerServices where isNull((
SELECT MAX(invoiceid)
FROM Invoices
LEFT JOIN InvoicesHistory
ON InvoicesHistory.ServiceHistoryID = Invoices.ServiceHistoryID
WHERE serviceID = Invoices.serviceID
),0)=0
Please let me know if you want me to add more information.
I think you just want not exists:
select cs.*
from CustomerServices cs
where not exists (select 1
from Invoices i left join
InvoicesHistory ih
on ih.ServiceHistoryID = i.ServiceHistoryID
where cs.serviceID = i.serviceID
);
In your case, the nested WHERE clause is not doing anything. It is equivalent to:
Invoices.serviceID = Invoices.serviceID
by the scoping rules in SQL. In all likelihood, this is intended to be a correlation clause and hence needs a qualified column name.
I am learning SQL (bit by bit!) trying to perform a query on our database and adding in a count function to show the total orders that appear against a customers id by counting in a inner join query.
Somehow it is pooling all the data together onto one customer with the count function though.
Can someone please suggest where I am going wrong?
SELECT tbl_customers.*, tbl_stateprov.stprv_Name, tbl_custstate.CustSt_Destination, COUNT(order_id) as total
FROM tbl_stateprov
INNER JOIN (tbl_customers
INNER JOIN (tbl_custstate
INNER JOIN tbl_orders ON tbl_orders.order_CustomerID = tbl_custstate.CustSt_Cust_ID)
ON tbl_customers.cst_ID = tbl_custstate.CustSt_Cust_ID)
ON tbl_stateprov.stprv_ID = tbl_custstate.CustSt_StPrv_ID
WHERE tbl_custstate.CustSt_Destination='BillTo'
AND cst_LastName LIKE '#URL.Alpha#%'
You need a GROUP BY clause in this statement in order to get what you want. You need to figure out what level you want to group it by in order to select which fields to add to the group by clause. If you just wanted to see it on a per customer basis, and the customers table had an id field, it would look like this (at the very end of your sql):
GROUP BY tbl_customers.id
Now you can certainly group by more fields, it just depends how you want to slice the results.
In your select statement you are using format like tableName.ColumnName but not for COUNT(order_id)
It should be COUNT(tableOrAlias.order_id)
Hope that helps.
As you are new to SQL it might also be worth considering the readability of your joins - the nested / bracketed joins you mentioned above are quite hard to read, and I would also personally alias your tables to make the query that bit more accessible:
SELECT
tbl_customers.customer_id
,tbl_stateprov.stprv_Name
,tbl_custstate.CustSt_Destination
,COUNT(order_id) as total
FROM tbl_stateprov statep
INNER JOIN tbl_custstate state ON statep.stprv_ID = state.CustSt_StPrv_ID
INNER JOIN tbl_customers customer ON customer.cst_ID = state.CustSt_Cust_ID
INNER JOIN tbl_orders orders ON orders.order_CustomerID = state.CustSt_Cust_ID
WHERE tbl_custstate.CustSt_Destination='BillTo'
AND cst_LastName LIKE '#URL.Alpha#%'
GROUP BY
tbl_customers.customer_id
,tbl_stateprov.stprv_Name
,tbl_custstate.CustSt_Destination
--And any other columns you want to include the count for
I am attempting to get the information from one table (games) and count the entries in another table (tickets) that correspond to each entry in the first. I want each entry in the first table to be returned even if there aren't any entries in the second. My query is as follows:
SELECT g.*, count(*)
FROM games g, tickets t
WHERE (t.game_number = g.game_number
OR NOT EXISTS (SELECT * FROM tickets t2 WHERE t2.game_number=g.game_number))
GROUP BY t.game_number;
What am I doing wrong?
You need to do a left-join:
SELECT g.Game_Number, g.PutColumnsHere, count(t.Game_Number)
FROM games g
LEFT JOIN tickets t ON g.Game_Number = t.Game_Number
GROUP BY g.Game_Number, g.PutColumnsHere
Alternatively, I think this is a little clearer with a correlated subquery:
SELECT g.Game_Number, G.PutColumnsHere,
(SELECT COUNT(*) FROM Tickets T WHERE t.Game_Number = g.Game_Number) Tickets_Count
FROM Games g
Just make sure you check the query plan to confirm that the optimizer interprets this well.
You need to learn more about how to use joins in SQL:
SELECT g.*, count(*)
FROM games g
LEFT OUTER JOIN tickets t
USING (game_number)
GROUP BY g.game_number;
Note that unlike some database brands, MySQL permits you to list many columns in the select-list even if you only GROUP BY their primary key. As long as the columns in your select-list are functionally dependent on the GROUP BY column, the result is unambiguous.
Other brands of database (Microsoft, Firebird, etc.) give you an error if you list any columns in the select-list without including them in GROUP BY or in an aggregate function.
"FROM games g, tickets t" is the problem line. This performs an inner join. Any where clause can't add on to this. I think you want a LEFT OUTER JOIN.