I have two tables, Customer and Sales.
I have to select customer and salesperson in the query. I have combined both the tables with the primary key with customer ID .
I also have to filter the selected data where salesperson name is ‘ John’ and ‘jack ,
When I use
where salesperson = ‘John’ and ‘jack’
I am getting no results.
Please help me on how to get salesperson with names from jack and John .
You would use in:
where salesperson in ('John', 'Jack')
This is logically equivalent to:
where salesperson = 'John' or salesperson = 'Jack'
But in is simpler to write and less error-prone.
If you want customers that have been associated with both John and Jack, then you would combine this with aggregation:
select customerid
from sales
where salesperson in ('John', 'Jack')
group by customerid
having count(distinct salesperson) = 2;
That is, look for customers that have either saleperson. Aggregate and return only the customers that have had both.
AND is correct. Using OR as wouter suggests will output the result if 1 condition is matched so probably not what you want. Perhaps paste the full code here for better help. Have you tested just 1 name or OR just to ensure your query is working?
I am working with a table that contains Account_No as unique ID, Customer_Name, Building_Name. The table below is an example:
It can be seen for few cases there are same customer name and same building however different Account_No. I need to remove duplicate names even though they have unique Account_No. Building_Name and Customer_Name are ties together. For example "William----Science City" and "William-----River Club" should be count as two customers since they are residing in different buildings. The result table should look as below;
I need to use SQL for creating the resulting table. Kindly use Customer Table as the reference for SQL query. Thanks
Select Min(Account_No) As Account_No
,Customer_Name,Building_Name
From Customer_Table
Group By Customer_Name, Building_Name
I am kind of new to SQL and I made a couple of tables to practice. The columns may have some unrelated categories but I don't know what else write...
Anyway, basically what i want to do is get info from two tables based on the first and last name from one table.
Here are my tables:
Order
Host
I want create a query to pull the ticket number, height, order, subtotal and total by first and last name. The only orders I want to pull are from John Smith And Sam Ting. So in the end, I want my extraction to have the following columns:
Ticket Number
First Name
Last Name
Height
Order
Subtotal
Total
Any help or direction would be awesome!
With the assumption the tables both have unique Ticket_Numbers and that will provide a one-to-one mapping between then.
SELECT
Order.Ticket_Number,
First_Name,
Last_Name,
Height,
Order,
Subtotal,
Total
FROM Order
JOIN Host on Host.Ticket_Number = Order.Ticket_Number
WHERE
(First_Name = 'John' AND Last_Name = 'Smith')
OR (First_Name = 'Sam' AND Last_Name = 'Ting')
You need to "call" the table name first, and then the column. After that you need to use the "join" for the 2 tables. And finally you need the "where". I didn't look for the details so you need to check the "names".
SELECT Order.Ticket_Number, Order.First_Name, Order.Last_Name, Order.Height, Order.Order, Cost.Subtotal, Cost.Total
FROM Order
INNER JOIN Cost
where First_Name="Jhon" and Last_Name="blablabla"
or
First_Name="SecondGuy" and Last_Name="blablabla"
It wont let me upload image but columns are OrderID, CustomerName, CustomerAddress, ProductNumber, SellDate, ProductDescription
I am trying to teach myself SQL. Could someone please help me identify a few things?
1) I want to write a SQL statement that retrieves the customer name and address of the customer that placed order 7.
Is this right?
Select CustomerName, Address
From Order
Where OrderID = ‘7’
2)Next I want to write an SQL statement that adds a new order to the Order table.
Is this right?
INSERT INTO order(OrderID, CustomerName, CustomerAddress, ProductNumber, SellDate, ProductDescription)
VALUES (8, 'Ben C', '12 Kents Road', 01/15/2012, Clay :));
3) What is wrong with this data model and how would you redesign it? I really need help here. Does it need to be sorted? How could I describe a new high level design?
4) How would I move this data from an old model to a new model?
5)Using the new data model, I need to write a JOIN that retrieves the customer name and address of the customer that placed order 7. I have not gotten here yet because I am not sure why the old data model is bad.
First, you need to answer a question:
Can a customer place more than one order? If your answer is 'yes', would you like to have a customer catalog?
In this scenario, you need to normalize your database. First of all, you need to separate the data into logical sets; in this case, Customers, Products and Orders... I will asume that an order can have one or more products.
Then, design your tables (I will use MySQL style for the code):
Your customers catalog:
create table tbl_customers (
customerId int not null primary key,
customerName varchar(100),
customerAdress varchar(200)
);
Your products catalog:
create table tbl_products (
productNumber int not null primary key,
productName varchar(100),
);
Your orders catalog:
create table tbl_orders (
orderId int not null primary key,
orderDate date,
customerId int unsigned not null
);
For each order, you will need to know how many 'units' of which products you will be ordering:
create table tbl_orders_products (
orderProductId int not null primary key,
orderId int not null,
productNumber int not null,
units int,
);
After this, you will populate your tables with your data, and then you can perform whichever query fits you.
A few notes:
tbl_orders is related with tbl_customers... your customer's data will have to be inserted in tbl_customers before he can place an order.
Before you insert the order's details, you will need to create the order
Before you insert the order's details, you will need to populate tbl_products
This is just a way to solve it.
Hope this helps you
Now, if you want to move to this model, you have some work to do:
Populate your products catalog: insert into tbl_products values (1,'productA'), (2, 'productB'), ...
Populate your customers catalog
Then you can start placing your orders. I'll asume that you have the following customers:
customerId | customerName | customerAdress
---------------------------------------------
1 | John Doe | 31 elm street
2 | Jane Doe | 1223 park street
... and products:
productNumber | productName
------------------------------
1000 | Pencil
2000 | Paper clip
3000 | Bottled water
Now, placing an order is a two-step process: first, create the order record, and then insert the order details:
The order (Customer John Doe): insert into tbl_orders values (1, '2012-10-17', 1);
The order details (one pencil, ten paper clips): insert into tbl_orders_products values (1, 1, 1000, 1), (2, 1, 2000, 10);
Now, to select the customer for order seven (as stated in your question), you can use the following query:
select c.*
from tbl_customers as c
inner join tbl_orders as o on c.customerId = o.customerId
where o.orderId = 7;
This is just a start point. You should look for good books or online tutorials (w3 tutorials can be a good online 'place' to start).
Although I don't quite like MS Access, it's a good program to learn the basics of sql, and there're a lot of books and learning resources for it. Note: I don't like Access, and I don't mean to advertise it, but it might be a good learning tool.
First you need to normalise, there 's a lot of stuff around that, but loads of tutorials that try and take some common sense and make it really obscure
Looking at your column names I see three tables
Customers(CustomerID, CustomerName, CustomerAddress)
CustomerOrders(OrderID, CustomerID, SellDate, ProductNumber) Try not to name your tables and columns and such the same as Sql keywords.
Products(ProductNumber, ProductDescription)
Normalisation says things like, you should be able to uniquely identify any records in the table, you had that with OrderId. When I split the tables up I added CustomerID, because you could have more than one customer with the same name.
Another simple rule is in your structure, if you had more than one order for a customer, you would be storing their name and address more than once, which is wasteful, but the real problem, is what if that customer changes address? How do you find which rows to change, you could do Where name = "Fred" and Address = "Here", but you don't know if you have more than one customer called Fred with an address of Here.
So you first query would be a join
Select Customers.CustomerName,Customers.CustomerAddress From Customers
Inner join CustomerOrders On Customers.CustomerID = CustomerOrders.CustomerID
Where CustomerOrders.OrderID = 7
Or if you want to skip past learning joins for now, you could do it with two queries
Select CustomerID From CustomerOrders Where OrderID = 7
then
Select CustomerName,CustomerAddress From Customers Where CustomerID = ?
You should be using joins, but you might find sub-query a little easier to get your head round. You can do both queries at once with
Select CustomerID From CustomerOrders
Where CustomerID In (Select CustomerID From CustomerOrders Where OrderID = 7)
Don't know far you've got with sql table creation, but Primary and Foreign keys is two things to look at. That will let you put some rules in the database. A primary Key on CustomerOrders will stop you having two orders with the same ID, which would be bad.
A foreign Key would stop you creating a CustomerOrder for a customer that did not exist, and one to products for a product that doesn't.
Assuming you went down that route and you were looking to write an application to order things.
You'd probably have a function to maintain Customers which would add them with something like
Insert Into Customers(CustomerID,CustomerName,CustomerAddress) Values(1,'Fred Bloggs','England')
And one For Products
Insert Into Products(ProductNumber,ProductDescription) Values(1,'A thingamabob')
Then you'd choose a customer, so you have it's id, select a product so you have it's number, so you don't need to mess with CustomerName, CustomerAddress or ProductDescription
and
Insert Into CustomerOrders(OrderID,CustomerID,ProductNumber,SellDate) Values(1,1,1,'20121017')
Note the date format, if you are going to pass dates as strings to sql, (another topic this) do them in YYYYMMDD, when you get them back out with a select, you'll get them in the format your machine/database is set up for which in your case seems to be mm/dd/yyyy. The problem is I deduced that because I know there are only twelve months in the year. (One of the things that makes me a senior dev :) If your example selldate had been 1/5/2012, I'd have read that as the 1st May, because I'm configured for English. Avoid that ambiguity at all costs it will reach out and hurt you on a regular basis.
PS the way you did it 1/15/2012 would be treated as a mathematical expression as in 1 divided by 15 ...
So the reason you couldn't write a join is basically you only had one table. Join is join one table to another. Well actually it's a bit more complex than that, but that's a good way past where you are in the learning curve.
As for moving the data, be quicker to start again I should think. Unlikely you have created two different customers with the same name, but the queries to move the data, would have to take into account that you could have.
To move the data, assuming CustomerID is an Identity (Autonumber) column
Something like
Insert into Customers(CustomerName,CustomerAddress)
Select Distinct CustomerName,CustomerAddress From [Order]
Would do the job for Customers.
Then for products
Insert into Products(ProductDescription)
Select Distinct ProductDescription From [Order]
Then
Insert into CustomerOrders(OrderID,CustomerID,ProductNumber,SellDate)
Select old.OrderID,c.CustomerID,p.ProductNumber,old.SellDate
From [Order] old
Inner Join Products p On p.ProductDesription = old.ProductDescription
Inner Join Customers c On c.CustomerName = old.CustomerName And c.CustomerAddress = old.CustomerAddress
might do CustomerOrders I think
A simple tip. When modelling a data solution, try to write down simple sentences that describe the scenario. For example (ok, it is just a basic one):
An order is made up of many order lines
An order line refers a product
A customer create many orders
Here, the nouns describe the entities of your scenario. Then, for each entity, try to describe its property:
An order is characterized by a unique serial number, a date, a total. It refers a customer.
An order line refers to a product, and is characterized by a quantity, a unit price, a sub total
A customer....
An so on.
Well, in your model you roughly have to create a table for each entity. The table fields are taken from the property of each entity. For each field remeber to define the proper data type.
Ok, this is NOT a modelling tutorial, but it is a starting point, just to approach the solution.
Here's my question: how do I maintain record integrity using aggregate functions with a group by?
To explain further, here's an example.
I have a table with the following columns: (Think of it as an "order" table)
Customer_Summary (first 10 char of name + first 10 char of address)
Customer_Name
Customer_Address
Customer_Postal Code
Order_weekday
There is one row per "order", so many rows with the same customer name, address, and summary.
What I want to do is show the customer's name, address, and postal code, as well as the number of orders they've placed on each weekday, grouped by the customer's summary.
So the data should look like:
Summary | Name | Address | PCode | Monday | Tuesday | Wednesday | Thursday | Friday
test custntest addre|test custname|test address|123456 | 1 | 1 | 1 | 1 | 1
I only want to group records of similar customer summary together, but obviously I want one name, address, and postal code to show. I'm using min() at the moment, so my query looks like:
SELECT Customer_Summary, min(customer_name), min(customer_address), min(customer_postal_code)
FROM Order
Group by customer_summary
I've omitted my weekday logic as I didn't think it was necessary.
My issue is this - some of these customers with the same customer summary have different addresses and postal codes.
So I might have two customers, looking like:
test custntest addre|test custname |test address |323456|
test custntest addre|test custname2|test address2|123456|
Using the group by, my query will return the following:
test custntest addre|test custname |test address |123456|
Since I'm using min, it's going to give me the minimum value for all of the fields, but not necessarily from the same record. So I've lost my record integrity here - the address and name returned by the query do not correctly match the postal code.
So how do I maintain data integrity on non-grouped fields when using a group by clause?
Hopefully I explained it clearly enough, and thanks in advance for the help.
EDIT: Solved. Thanks everyone!
You can always use ROW_NUMBER instead of GROUP BY
WITH A AS (
SELECT Customer_Summary, customer_name, customer_address, customer_postal_code,
ROW_NUMBER() OVER (PARTITION BY Customer_Summary ORDER BY customer_name, customer_address) AS rn
FROM Order
)
SELECT Customer_Summary, customer_name, customer_address, customer_postal_code
FROM A
WHERE rn = 1
Then you are free to order which customer to use in the ORDER BY clause. Currently I am order them by name and then address.
Edit:
My solution does what you asked for. But I surely agree with the others: If you are allowed to change the database structure, this would be a good idea... which you are not (saw your comment). Well, then ROW_NUMBER() is a good way.
I think you need to re-think your structure.
Ideally you would have a Customer table with an unique ID. Then you would use that unique ID in the Order table. Then you don't need the strange "first 10 characters" method that you are using. Instead, you just group by the unique ID from the Customer table.
You could even then also have a separate table for addresses, relating each address to the customer, with multiple rows (with fields marking them as home address, delivery address, billing address, etc).
This way you separate the Customer information from the Address information and from the Order information. Such that if the customer changes name (marriage) or address (moving home) you don't break your data - Everything is related by the IDs, not the data itself.
[This relationship is known as a Foreign Key.]