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"
Related
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?
so I've been struggling with some of the select statements on multiple tables:
Employee table
Employee_ID
First_Name
Last_Name
Assignment table
Assignment_ID
Employee_ID
Host_Country_arrival_Date
Host_Country_departure_Date
Scheduled_End_Date
I'm being asked to display query to display employee full name, number of days between the host country arrival date and host country departure date, number of days between today's date and the assignment scheduled end date and the results sorted according to host country arrival date with the oldest date on top.
also, I'm not familiar with the sort function in SQL server..
Here's my query and I've been getting syntax errors:
SELECT
First_Name
Last_Name
FROM Employee
SELECT
Host_Country_Arrival_Date
Host_Country_Departure_Date
FROM Assignment;
So, Basically what your code is doing is 2 different queries. The first getting all the employees names, and the second one getting the dates of the assignments.
What you'll want to do here is take advantage of the relationship between the tables using a JOIN. That is basically saying "Give me all employees and all of HIS/HERS assignments". So, for each assignment that the employee has, it will bring a row in the result with his name and the assignment info.
To get the difference between days you use DATEDIFF passing 3 parameters, the timespan in which to calculate the difference, the first and the second date. It will then Subtract the first one from the second one and give you the result in the selected timespan.
And finnaly the sorting: Just add 'ORDER BY' followed by each column that you want to use for ordering and then specify if you want it ascending (ASC) or descending (DESC).
You can check how I would answer the if that question was proposed to me in a coding challenge.
SELECT
CONCAT(E.First_Name,' ', E.Last_Name) FullName,
DATEDIFF(DAY,Scheduled_End_Date,getdate()) DaysTillScheduledDate,
DATEDIFF(DAY,Host_Country_Arrival_Date,Host_Country_Departure_Date) DaysTillScheduledDate
FROM Employee As E --Is nice to add aliases
Inner Join
Assignment As A
on E.Employee_ID = A.Employee_ID -- Read a little bit about joins, there are a lot of material availabel an its going to be really necessary moving forward with SQL
order by Host_Country_Arrival_Date DESC -- Just put the field that you want to order by here, desc indicates that it should be descending
You should use a JOIN to link the tables together on Employee_ID:
SELECT
First_Name,
Last_Name,
Host_Country_Arrival_Date,
Host_Country_Departure_Date
FROM Employee
JOIN Assignment ON Assignment.Employee_ID = Employee.Employee_ID;
What this is saying basically is that for each employee, go out to the assignments table and add the assignments for that employee. If there are multiple assignments, the employee columns will be repeated on each row with the assignment columns for the assignment.
You need to look for the join and group by. Please find this link for reference tutorial
For now you may try this...
SELECT
CONCAT(Emp.First_Name,' ', Emp.Last_Name) FullName,
DATEDIFF(DAY,Scheduled_End_Date,getdate()) DaysTillScheduledDate,
DATEDIFF(DAY,Host_Country_Arrival_Date,Host_Country_Departure_Date) DaysTillScheduledDate
FROM Employee As Emp Inner Join Assignment As Assign on Emp.Employee_ID = Assign.Employee_ID
order by Host_Country_Arrival_Date DESC
I have a table with customers, and a table with cities.
In the customers table, the city_id is related to the id_city of the cities table.
Other fields in the tables
customers: name, surname
cities: ext_code, description, address_code
The problem is that I have thousands of customers records related to cities in which the ext_code is not present.
The cities table, elsewhere, contains a lot of duplicated records; in the duplicated sets only one record has a valid ext_code.
The problem is: substitute the city_id with a id_city that contains a valid ext_code. The only fields to evaluate to group cities are address_code or description.
Any suggestion?
If the
only fields to evaluate to group cities are address_code or
description
then that's what you should use to join your data on while filtering out the non "valid ext_code" that you mentioned.
Here is a crude way to do a one time update of customer.
You will need to tweak the code to make it work with your system, but that should be easy enough.
UPDATE Customer
SET CityID =
(
--This bit will find cities that look like the one we already have,
SELECT TOP 1 CityID
FROM City AS X
WHERE X.AddressCode = City.AddressCode
OR X.Description = City.Description
ORDER BY X.ExtCode DESC --This puts nulls last!
)
FROM Customer
INNER JOIN City ON City.CityID = Customer.CityID
Say I have a student table with the following fields - student id, student name, age, gender, marks, class.Assume that due to some error, there are multiple entries corresponding to each student. My requirement is to identify the duplicate rows in the table and the filter criterion is the student name and the class.But in the query result, in addition to identifying the duplicate records, I also need to find the original student detail which got duplicated. Is there any method to do this. I went through this answer: SQL: How to find duplicates based on two fields?. But here it only specifies how to find the duplicate rows and not a means to identify the actual row that was duplicated. Kindly throw some light on the possible solution. Thanks.
First of all: if the columns you've listed are all in the same table, it looks like your database structure could use some normalization.
In terms of your question: I'm assuming your StudentID field is a database generated, primary key and so has not been duplicated. (If this is not the case, I think you have bigger problems than just duplicates).
I'm also assuming the duplicate row has a higher value for StudentID than the original row.
I think the following should work (Note: I haven't created a table to verify this so it might not be perfect straight away. If it doesn't it should be fairly close)
select dup.StudentID as DuplicateStudentID
dup.StudentName, dup.Age, dup.Gender, dup.Marks, dup.Class,
orig.StudentID as OriginalStudentId
from StudentTable dup
inner join (
-- Find first student record for each unique combination
select Min(StudentId) as StudentID, StudentName, Age, Gender, Marks, Class
from StudentTable t
group by StudentName, Age, Gender, Marks, Class
) orig on dup.StudentName = orig.StudenName
and dup.Age = orig.Age
and dup.Gender = orig.Gender
and dup.Marks = orig.Marks
and dup.Class = orig.Class
and dup.StudentID > orig.StudentID -- Don't identify the original record as a duplicate
I am having difficulty updating records within a database based on the most recent date and am looking for some guidance. By the way, I am new to SQL.
As background, I have a windows forms application with SQL Express and am using ADO.NET to interact with the database. The application is designed to enable the user to track employee attendance on various courses that must be attended on a periodic basis (e.g. every 6 months, every year etc.). For example, they can pull back data to see the last time employees attended a given course and also update attendance dates if an employee has recently completed a course.
I have three data tables:
EmployeeDetailsTable - simple list of employees names, email address etc., each with unique ID
CourseDetailsTable - simple list of courses, each with unique ID (e.g. 1, 2, 3 etc.)
AttendanceRecordsTable - has 3 columns { EmployeeID, CourseID, AttendanceDate, Comments }
For any given course, an employee will have an attendance history i.e. if the course needs to be attended each year then they will have one record for as many years as they have been at the company.
What I want to be able to do is to update the 'Comments' field for a given employee and given course based on the most recent attendance date. What is the 'correct' SQL syntax for this?
I have tried many things (like below) but cannot get it to work:
UPDATE AttendanceRecordsTable
SET Comments = #Comments
WHERE AttendanceRecordsTable.EmployeeID = (SELECT EmployeeDetailsTable.EmployeeID FROM EmployeeDetailsTable WHERE (EmployeeDetailsTable.LastName =#ParameterLastName AND EmployeeDetailsTable.FirstName =#ParameterFirstName)
AND AttendanceRecordsTable.CourseID = (SELECT CourseDetailsTable.CourseID FROM CourseDetailsTable WHERE CourseDetailsTable.CourseName =#CourseName))
GROUP BY MAX(AttendanceRecordsTable.LastDate)
After much googling, I discovered that MAX is an aggregate function and so I need to use GROUP BY. I have also tried using the HAVING keyword but without success.
Can anybody point me in the right direction? What is the 'conventional' syntax to update a database record based on the most recent date?
So you want to update the AttendantsRecordsTable, and set the comment to the comment in the most recent CourseDetailsTable for each employee?
UPDATE
dbo.AttendanceRecordsTable
SET
Comments = #Comments
FROM
CourseDetailsTable cd
INNER JOIN
Employee e ON e.EmployeeID = AttendanceRecordTable.EmployeeID
WHERE
e.LastName = #LastName
AND e.FirstName = #FirstName
AND cd.CourseName = #CourseName
AND AttendanceRecordsTable.CourseID = cd.CourseID
AND AttendanceRecordsTable.LastDate =
(SELECT MAX(LastDate)
FROM AttendanceRecordsTable a
WHERE a.EmployeeID = e.EmployeeID
AND a.CourseID = cd.CourseID)
I think something like that should work.
You basically need to do a join between the AttendanceRecordTable, which you want to update, and the Employee and CourseDetailsTable tables. For these two, you have defined certain parameters to select a single row each, and then you need to make sure to update only that last AttendanceRecordTable entry which you do by making sure it's the MAX(LastDate) of the table.
The subselect here:
(SELECT MAX(LastDate)
FROM AttendanceRecordsTable a
WHERE a.EmployeeID = e.EmployeeID AND a.CourseID = cd.CourseID)
will select the MAX (last) of the LastDate entries in AttendanceRecordsTable, based on selection of a given employee (e.EmployeeID) and a given course (cd.CourseID).
Pair that with the selects to select the single employee by first name and last name (that of course only works if you never have two John Miller in your employee table!). You also select the course by means of the course name, so that too must be unique - otherwise you'll get multiple hits in the course table.
Marc
Assuming that you primary key on the AttendanceRecordsTable is id:
UPDATE AttendanceRecordsTable SET Comments = #Comments
WHERE AttendanceRecordsTable.id = (
SELECT AttendanceRecordsTable.id
FROM EmployeeDetailsTable
JOIN AttendanceRecordsTable ON AttendanceRecordsTable.EmployeeID = EmployeeDetailsTable.EmployeeID·
JOIN CourseDetailsTable ON AttendanceRecordsTable.CourseID = CourseDetailsTable.CourseID
WHERE
EmployeeDetailsTable.LastName =#ParameterLastName AND EmployeeDetailsTable.FirstName =#ParameterFirstName AND
CourseDetailsTable.CourseName =#CourseName
ORDER BY AttendanceRecordsTable.LastDate DESC LIMIT 1)
Basically, that sub select will first join the attendence, employee and coursedetail tables, extract those rows where the employee's and course details' name match those given by your parameters and limit the output in reverted order to one line. You might want to test that sub-select statement first.
Edit: I just read your posting again, you don't have a single primary key column on AttendanceRecordsTable. Bummer.