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C# Windows Forms inner join three tables

I have a problem with SQL query in C#.
In my database I have tables: Supplier, ApplicationForm, SupplierAdress. I was trying to join these three tables but I got an syntax error with the inner join.
Also my method in C# have input parameter AppFormID. With that parameter I have to open particular Application Form from database on Windows app.
This is my SQL query:
command.CommandText = "select ApplicationForm.Date,ApplicationForm.About,ApplicationForm.Supplier," +
" Supplier.IDSupplier,Supplier.Name,Supplier.Email,Supplier.Phone," +
" Supplier.SupplierAdress,SupplierAdress.AdressID,SupplierAdress.Name" +
" from ApplicationForm" +
" inner join Supplier on ApplicationForm.Supplier=Supplier.IDSupplier" +
" inner join SupplierAdress on ApplicationForm.Supplier.SupplierAdress = SupplierAdress .AdressID" +
" where ApplicationForm.ApplicatonFormID=" + AppFormID;
I hope that someone will help me.

This is wrong ApplicationForm.Supplier.SupplierAdress
try this, dunno exact field names:
from
ApplicationForm
inner join Supplier on ApplicationForm.Supplier=Supplier.IDSupplier
inner join SupplierAdress on Supplier.IdAdress =SupplierAdress.AdressID

Using a left join where is null in the update statement

I'm trying to use a left join to set the plot.jobs row to 0 when there isn't a match found in the booking table (the check is plot.plot_id = booking.plot_id).
However I keep getting the following error message:
An exception of type 'MySql.Data.MySqlClient.MySqlException' occurred
in MySql.Data.dll but was not handled in user code Additional
information: You have an error in your SQL syntax; check the manual
that corresponds to your MySQL server version for the right syntax to
use near 'FROM plot LEFT JOIN booking ON plot.plot_id =
booking.plot_id WHERE plot.plot_id' at line 1.
I was following this template here:
UPDATE <Table2>
SET Count = 0
FROM <Table2>
LEFT JOIN <Table1>
ON <Table2>.<JoinColumn> = <Table1>.<JoinColumn>
WHERE <Table1>.<JoinColumn> IS NULL
This is my code so far:
query = "UPDATE plot SET jobs = #jobCount WHERE plot_id = #plotID AND postcode='MK';";
query += "UPDATE plot " +
"SET jobs = 0 " +
"FROM plot " +
"LEFT JOIN booking " +
"ON plot.plot_id = booking.plot_id " +
"WHERE plot.plot_id IS NULL";
cmd = new MySqlCommand(query, _connection);

You are attempting to use the SQL Server syntax for UPDATE statements on MySQL. This doesn't work.
The UPDATE-syntax of MySQL is:
UPDATE [LOW_PRIORITY] [IGNORE] table_reference
SET col_name1={expr1|DEFAULT} [, col_name2={expr2|DEFAULT}] ...
[WHERE where_condition]
[ORDER BY ...]
[LIMIT row_count]
Where table_reference is defined with the JOIN-syntax.
Your query should be something like:
query += "UPDATE plot " +
"LEFT JOIN booking " +
"ON plot.plot_id = booking.plot_id " +
"SET jobs = 0 " +
"WHERE plot.plot_id IS NULL";
I am wondering if you don't mean: WHERE booking.plot_id IS NULL

Your syntax isn't quite right for MySQL. Do your LEFT JOIN before SET
Something like this should work (Note: this hasn't been tested).
query += "UPDATE plot p" +
"LEFT JOIN booking b" +
"ON p.plot_id = b.plot_id " +
"SET jobs = 0 " +
"WHERE p.plot_id IS NULL";

You are attempting to update the plot table setting jobs equal to zero when plot_id is null? What is the point of the join in this case? You are attempting to join records based on a null value which seems highly invalid, and you're not using the joined table booking for anything. I recommend removing the join and the from statement is not valid in an update as Saggio mentioned.
query = "UPDATE plot SET jobs = #jobCount WHERE plot_id = #plotID AND postcode='MK';";
query +="UPDATE plot " +
"SET jobs = 0 " +
"LEFT JOIN booking ON plot.plot_id = booking.plot_id" +
"WHERE booking.plot_id IS NULL;";
cmd = new MySqlCommand(query, _connection);

Update Table From Select Statement Sql Query

I have three tables, one holds a list of available products with relevant details such as product price, the other holds orders and the last holds specific order details including the items purchased in an order.
I am trying to create a query to calculate the total price of an order by linking the two of the tables with an inner join and then updating the order table with the value. The code I have written contains syntax errors, being a novice I have probably made an obvious mistake but any help would be appreciated.
"SELECT Sum(ProductTable.prodPrice) AS Total, OrderDetailTable.orderID " +
"FROM ProductTable INNER JOIN OrderDetailTable " +
"ON ProductTable.prodID = OrderDetailTable.prodID " +
"GROUP BY OrderDetailTable.orderID " +
"HAVING OrderDetailTable.orderID = ? " +
"UPDATE OrderTable " +
"SET " +
"totalPrice = Total " +
"WHERE OrderTable.orderID = ? ";
I am using Access.
I also forgot to mention that the ? is represented using a Dataview parameter
pc.Add(new Parameter("?", TypeCode.Int32, basketId.ToString()));
EDIT: Using PaqoGomez's suggestion to declare Total as a value I now get the error : Syntax error (missing operator) in query expression '0WHERE OrderTable.orderID = ?'.

Comment made before OP described this as MS Access:
Haven't tried this but you had the Select and update the wrong way round. This should be quite close. Its been a while for me but you may need to change the FROM clause to reference the table you are updating and INNER JOIN the sub-select instead of the WHERE clause.
"UPDATE OrderTable " +
"SET totalPrice = Sum(ProductTable.prodPrice)" +
"FROM (" +
"SELECT OrderDetailTable.orderID, Sum(ProductTable.prodPrice)" +
"FROM ProductTable INNER JOIN OrderDetailTable " +
"ON ProductTable.prodID = OrderDetailTable.prodID " +
"GROUP BY OrderDetailTable.orderID " +
") x" +
"WHERE x.orderID = OrderTable.OrderId"
UPDATE :
Based on OPs update regarding MS Access you can do an update with a sub-query, but I think it depends on the version of MS Access you are using and how you do it. Posts below seem to indicate it's quite problematic:
SQL Subqueries (Microsoft Access SQL)
How do I perform update query with subquery in Access?
Can It Be Done - Access 2007 SQL Update Query Using a Subquery?

By declaring a variable you can save the total value so that you can use it in the later update.
declare #Total int;
SELECT #Total = Sum(ProductTable.prodPrice)
//...
"SET " +
"totalPrice = #Total "
You dont mention which database platform you are using, I'm assuming MSSQL, other platforms would require a slightly different syntax.
You might also be interested to know that if you use the # symbol you can have a multiline string. This would allow you to avoid the concatenation that you are doing. eg.
var sql = #"some
sql
string"

What is the difference between using a parameter and just putting a variable then convert it

So I'm retrieving data from the database using odbc. One of my fields, which was causing the problem, is AutoNumber. In my query when I use, '" convert.toint64(empid)"', I get an error of data type missmatch. But when I used parameter, it worked perfectly. Can someone tell me what is the difference. As far as I know, AutoNumber is a long integer and long int is 64, right?
here are both of my queries:
string cmdText = "SELECT p.projID, p.projName, a.wageperday " +
"FROM ((projects p INNER JOIN assigns a ON p.projID = a.projname) " +
"INNER JOIN empos e ON a.employeeID= e.ID) " +
"WHERE a.employeeID = ?";
OdbcCommand assignslist = new OdbcCommand(cmdText, _connection);
assignslist.Parameters.AddWithValue("#empID", empid);
OdbcDataReader readassigns = assignslist.ExecuteReader();
GridView1.DataSource = readassigns;
GridView1.DataBind();
(this one works fine)
string cmdText = "SELECT p.projID, p.projName, a.wageperday " +
"FROM ((projects p INNER JOIN assigns a ON p.projID = a.projname) " +
"INNER JOIN empos e ON a.employeeID= e.ID) " +
"WHERE a.employeeID = '" + convert.toint64( empid ) + "';
OdbcCommand assignslist = new OdbcCommand(cmdText, _connection);
OdbcDataReader readassigns = assignslist.ExecuteReader();
GridView1.DataSource = readassigns;
GridView1.DataBind();
for this one, i get an error even if I removed the conversion, I get an error.
One more question, I don't understand INNER JOIN perfectly and the above code was from a user here who helped me. I don't understand why did he use "FROM ((projects p INNER JOIN assigns a ON p.projID = a.projname) " +
"INNER JOIN empos e ON a.employeeID= e.ID)"
two brackets -- I mean a bracket inside a bracket. And if I wanna join a 4th or 5th table do I have to put it inside a bracket aside from the main bracket? An example would be much appreciated!

If a.employeeID is a number then your problem are the quotes and the concatenation of a number to a string.
"WHERE a.employeeID = " + convert.toint64(empid).ToString()
but this make no sense because you have a string to build so, you could simply write
"WHERE a.employeeID = " + empid.ToString();
however use always the parameterized query. That is the correct way to go.
A parameterized query allows the Framework code to pass the parameters with the correct format and you don't have to worry about quoting values, format of dates and decimal separators. (And last but not least, you avoid any possibilities of Sql Injection)
For the second part of your question, JOIN is used to put togheter data from two tables, when you have more than one JOIN the parenthesys help to understand how the grouping from the tables are perfomed. First the data from projects and assigns are grouped together following the rules of the INNER JOIN then the resulting set of data is joined with the data from the employee table following the rules of the second join.

In your second query, instead of using convert.toint64( empid ) try using empid.ToString():
"WHERE a.employeeID = " + empid.ToString();
The error you were receiving was due to the fact that you were trying to concatenate a string with an integer.
With regards to the INNER JOINs you are using, the use of the brackets is dependant upon the database you are using. In most cases, you will not need the brackets at all and they can be removed without any issue, so you could rewrite the query to:
string cmdText = "SELECT p.projID, p.projName, a.wageperday " +
"FROM projects p " +
"INNER JOIN assigns a ON p.projID = a.projname " +
"INNER JOIN empos e ON a.employeeID = e.ID " +
"WHERE a.employeeID = " empid.ToString();

You're trying to add a string and an integer, which isn't allowed automatically. You'd have to convert the number to a string first, like this:
"WHERE a.employeeID = '" + empid.ToString() + "';
But, using parameters is the better way for other reasons (best habit to be in, to avoid SQL-injection attacks, etc.).

SQL error in C#

conn.Open();
String sql = "select CATEGORIES.CAT_NAME,PRODUCTS.PRO_MODEL,PRODUCTS.PRO_NAME,PRODUCTS.PRO_PRICE,PRODUCTS.PRO_IMAGE,PRODUCTS.PRO_DESCRIPTION,PRODUCTS.PRO_STATUS,PRODUCTS.PRO_ACTIVE" +
"from PRODUCTS INNER JOIN CATEGORIES on PRODUCTS.CAT_ID = CATEGORIES.CAT_ID";
My Query SQL runs fine in MYSQL Server but it has error in C# code Incorrect syntax near the keyword 'INNER'. hope have answer soon

You need to add space between (.PRO_ACTIVE" and "from) string concatenation.
.PRO_ACTIVE " + "from...
So your query should be:
String sql = "select CATEGORIES.CAT_NAME,PRODUCTS.PRO_MODEL,PRODUCTS.PRO_NAME,PRODUCTS.PRO_PRICE,PRODUCTS.PRO_IMAGE,PRODUCTS.PRO_DESCRIPTION,PRODUCTS.PRO_STATUS,PRODUCTS.PRO_ACTIVE"
+ " " +//explicit space
"from PRODUCTS INNER JOIN CATEGORIES on PRODUCTS.CAT_ID = CATEGORIES.CAT_ID";

You need a space at the end of the first line of your string -- C# doesn't put line feeds in.

change it to:
String sql = "select CATEGORIES.CAT_NAME,PRODUCTS.PRO_MODEL,PRODUCTS.PRO_NAME,PRODUCTS.PRO_PRICE,PRODUCTS.PRO_IMAGE,PRODUCTS.PRO_DESCRIPTION,PRODUCTS.PRO_STATUS,PRODUCTS.PRO_ACTIVE" +
" from PRODUCTS INNER JOIN CATEGORIES on PRODUCTS.CAT_ID = CATEGORIES.CAT_ID";
A space was missing between "..PRODUCTS.PRO_ACTIVE" and "from PRODUCTS.."