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How to grab last row in database table with specific requirements?

Okay so I am accepting payments on my site (via Authorize.Net). The payment form redirects to a receipt page.
I will have a column in the database for an invoice code (column InvoiceCode), which is RRC0A in this instance. Then I will have another column for an 8 digit number (column InvoiceNumber). Then I will have InvoiceCode + InvoiceNumber = InvoiceId. For example, the InvoiceId will be RRC0A + 8 numbers. It will increment as such: 00000000, 00000001, 00000002, etc. Therefore the InvoiceId will be RRC0A00000001. I cannot simply increment the column in my database because there will be other InvoiceCodes that also start at 00000000.
I need to increment the InvoiceNumber by one when I add a new row. How can I grab the last InvoiceNumber that was entered into the database? It must be associated with the InvoiceCode RRC0A. This could occur when more than 1 person is making a payment, so I am not sure of the best way.
How can I pad the incrementing InvoiceNumber with 0's in front so that it is always 8 digits?

Using an identity and a computed column you can created you invoice numbers with the correct formatting at the time of insert.
CREATE TABLE [dbo].[Invoices](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Code] [nchar](5) NOT NULL,
[InvoiceNumber] AS ([Code]+right('00000000'+CONVERT([nvarchar](10),[ID]),(8))) PERSISTED,
[Cost] [decimal](18, 2) NOT NULL,
CONSTRAINT [PK_Invoices] PRIMARY KEY CLUSTERED
(
[ID] ASC
)
)
sample bulk insert
INSERT INTO [dbo].[Invoices] ([Code], [Cost])
OUTPUT INSERTED.*
SELECT 'ABC01', 500 UNION ALL
SELECT 'ABC01', 501 UNION ALL
SELECT 'EFG23', 502 UNION ALL
SELECT 'RRAc1', 503 UNION ALL
SELECT 'ABC01', 504
output
ID Code InvoiceNumber Cost
1 ABC01 ABC0100000001 500.00
2 ABC01 ABC0100000002 501.00
3 EFG23 EFG2300000003 502.00
4 RRAc1 RRAc100000004 503.00
5 ABC01 ABC0100000005 504.00
When you insert your records you can get the ID and InvoiceNumber back at the same time.
The values are also persisted so they may be indexed as you would other columns.

SELECT InvoiceCode, MAX(InvoiceID)
FROM yourTable t
GROUP BY InvoiceCode
This should return the latest InvoiceID for each InvoiceCode, but you can add your own WHERE clause to filter it down
As for how to pad-left in sql, check out this answer.

A as in one column is just a bad design
Have composite PK
InvCode (varchar), InvInt (int)
declare #InvCode varchar(20) = 'RRC0A'
insert into invoice (InvCode, InvInt)
OUTPUT INSERTED.InvInt, INSERTED.InvCode
select #InvCode, isnull(max(InvInt),-1) + 1
from invoice
where InvCode = #InvCode;
The isnull will deal with the first one
A single statement is a transaction so I don't think two simultaneous could clobber
Even if they did the PK would be violated so the insert would fail
use a view or a computed column for the formatted invoice number
CREATE TABLE [dbo].[Invoice](
[InvCode] [varchar](10) NOT NULL,
[InvInt] [int] NOT NULL,
[Formatted] AS ([InvCode]+right('00000000'+CONVERT([nvarchar](10),[InvInt]),(8))),
CONSTRAINT [PK_Invoice] PRIMARY KEY CLUSTERED
(
[InvCode] ASC,
[InvInt] ASC
)

You can grab the last InvoiceNumber with a SELECT query.
You can pad the invoice number with the + sign to concatenate two strings, and then use RIGHT() to get the right-most 8 characters.

ASP.NET MVC 5 - LINQ Query to Select Data from Database

I'm working on a school project in ASP.NET MVC 5. The project is about creating a social network. After the user logs in, he will see all public posts on his newsfeed.
I am having issues, though, in showing the public posts' data from the database.
This is the script of the database :
create table Utilizador(
id_utilizador integer not null identity(1,1),
nome varchar(50) not null,
apelido varchar(50) not null,
username varchar(15) not null unique,
pass varchar(50) not null,
email varchar(50) not null unique,
sexo char(1) not null CHECK (sexo IN('M', 'F')),
país varchar(50) not null,
imagem_perfil varchar(50) not null,
data_nascimento date not null,
estado int not null default 2, --0->Bloqueado 1-Activo, 2-por activar
primary key (id_utilizador),
check (email LIKE '%#%.%')
)
create table Post(
id_post integer not null identity(1,1),
texto varchar(400) not null,
primary key(id_post)
)
create table Publish_Post(
id_post integer not null,
id_utilizador integer not null,
data timestamp not null,
primary key(id_post),
foreign key(id_post) references Post(id_post),
foreign key(id_utilizador) references Utilizador(id_utilizador)
)
create table Privacy(
id_privacidade integer not null identity(1,1), --> 1 public, 2 private
nome varchar(50) not null,
primary key(id_privacidade)
)
create table Have_Privacy(
id_post integer not null,
id_privacidade integer not null,
primary key(id_post),
foreign key(id_post) references Post(id_post),
foreign key(id_privacidade) references Privacidade(id_privacidade)
)
Let me explain why I create the database the way I do:
The user creates and publishes some posts that have will have a privacy value (1 or 2). After the user logs in, all public posts(1) should appear on his newsfeed.
So far I have this LINQ query in C#:
var id_posts = from p in db.Posts
select p.texto;
ViewBag.Posts = id_posts;
Can someone help me?
Thanks in advance :)

Just do this
var id_posts = from p in db.Posts
join hp in db.Have_Privacy on p.id_post equals hp.id_post
join prv in db.Privacy on hp.id_privacidade equals prv.id_privacidade
where prv.nome = 'Private'
select p.texto;
Tell how it goes

Why not just add a field in Post called isprivate with boolean type of BIT that determines if it's private or not and then use query for provided data with where clause:
var id_posts = from p in db.Posts
where isprivate == false
select p.texto;
If you want to have more than 2 types of privacy and just stick with DB schema you provided, you can go with a JOIN:
If id decides it is private:
var id_posts = from p in db.Posts
join hp in db.Have_Privacy on p.id_post equals hp.id_post
where hp.id_privacidade = 1
select p.texto;
If name decides it is private:
var id_posts = from p in db.Posts
join hp in db.Have_Privacy on p.id_post equals hp.id_post
join prv in db.Privacy on hp.id_privacidade equals prv.id_privacidade
where prv.nome = 'Private'
select p.texto;
Also please note that naming tables in one language and columns in other is considered as bad design. It's hard for others (in this example me) to read it, even if I know what it should mean.
Two last queries use your schema with no changes implemented.

SQL to Return Matched Records from Two Tables in a Certain Way

This question is built upon my earlier question, which may be seen at:
SQL Server Query: Get a List of Columns Which Don't Exist in Another Table's Field
I have the following data in the splanning_restricted_attributes table
groupid 1 = RoomArea,Disability,Shower (edit not CSV; one per/row**)
groupid 3 = Water,Shower(edit not CSV; one per row)
And my updated query is:
select COLUMN_NAME
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME='Splanning_RoomData2'
AND COLUMN_NAME NOT IN
(
SELECT ATTRIBUTENAME
FROM SPLANNING_RESTRICTED_ATTRIBUTES
where groupid != #session_groupid
)
This query kind of works except I had not factored in what would happen when two (or more) groups were allowed access to the same attributes. As executed, this query returns only RoomArea,Disability when session groupid is 1 and only water when session groupid is 3.
How can I modify so that if groupid is 1 or 3 then it should return Shower along with other attributes?
Thanks!
* Edit* The query should return appropriate values when session groupid is either 1 or 3. So if groupid is 1 then return: RoomArea,Disability,Shower ; if groupid is 3 then return Water,Shower
* Edit 2: DDL and some more info below*
[SPLANNING_ROOMDATA2]
[RoomArea] [nvarchar](254) NULL,
[Disability] [nvarchar](254) NULL,
[Shower] [nvarchar](254) NULL,
[Water] [nvarchar](254) NULL,
[splanning_restricted_attributes]
[attributename] [nvarchar](50) NOT NULL,
[groupid] [int] NOT NULL,
[splanning_groups]
[groupid] [int] IDENTITY(1,1) NOT NULL,
[groupname] [nvarchar](50) NOT NULL,
So both SPLANNING_ROOMDATA2 and splanning_groups tables will have representation in the splanning_restricted_attributes table in such a way that each row of the splanning_restricted_attributeswill have a groupid and one attributename per row.

Never mind. I ended up doing a UNION query:
cmd.CommandText =
#"select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where
TABLE_NAME='Splanning_RoomData2' AND COLUMN_NAME NOT IN
(SELECT ATTRIBUTENAME FROM SPLANNING_RESTRICTED_ATTRIBUTES)
UNION (SELECT ATTRIBUTENAME FROM SPLANNING_RESTRICTED_ATTRIBUTES
where groupid = #session_groupid)";
And I think the results are as expected. Phew!

Entity Framework, random query paging

This is what I want to achieve:
I want to query my db to return a list of entities
Randomize the list
Store the IDS of items received for future queries
Run a new query on the same table where the IDs are in the list that I have stored
Order by the list that I have stored.
I have managed to achieve step 1, 2, 3, 4 already but step 5 is difficult. Can anyone help me with a query like so:
SELECT *
FROM table_name
WHERE id IN (1,2,3,4....)
ORDER BY (1,2,3,4....)
Thanks in advance

Try
SELECT table_name.*
FROM crazy_sorted_table
LEFT JOIN
table_name ON crazy_sorted_table.ID=table_name.ID

A normal join (equi join) should do the trick , here is sample approach i tested:
/**crazyOrder filled 100 rows with random value from 1-250 in Id**/
CREATE TABLE [dbo].[crazyOrder] (
[Id] INT NOT NULL,
[Area] VARCHAR (50) NULL,
PRIMARY KEY CLUSTERED ([Id] ASC)
);
/**Normal order is filled with value from 1-100 sequentially in id**/
CREATE TABLE [dbo].[normalOrder] (
[Id] INT NOT NULL,
[Name] VARCHAR (50) NULL,
PRIMARY KEY CLUSTERED ([Id] ASC)
);
create table #tempOrder
(id int)
insert into #tempOrder
Select top 10 Id
from crazyOrder
order by NewID()
go
Select n.*
from normalOrder n
join #tempOrder t
on t.id = n.id
I was able to retrieve the rows in the same order as in the temp table (i used a data generator for the values)

Suggestion for a tag cloud algorithm

I have a MSSQL 2005 table:
[Companies](
[CompanyID] [int] IDENTITY(1,1) NOT NULL,
[Title] [nvarchar](128),
[Description] [nvarchar](256),
[Keywords] [nvarchar](256)
)
I want to generate a tag cloud for this companies. But I've saved all keywords in one column separated by commas. Any suggestions for how to generate tag cloud by most used keywords. There could be millions of companies approx ten keywords per company.
Thank you.

Step 1: separate the keywords into a proper relation (table).
CREATE TABLE Keywords (KeywordID int IDENTITY(1,1) NOT NULL
, Keyword NVARCHAR(256)
, constraint KeywordsPK primary key (KeywordID)
, constraint KeywordsUnique unique (Keyword));
Step 2: Map the many-to-many relation between companies and tags into a separate table, like all many-to-many relations:
CREATE TABLE CompanyKeywords (
CompanyID int not null
, KeywordID int not null
, constraint CompanyKeywords primary key (KeywordID, CompanyID)
, constraint CompanyKeyword_FK_Companies
foreign key (CompanyID)
references Companies(CompanyID)
, constraint CompanyKeyword_FK_Keywords
foreign key (KeywordID)
references Keywords (KeywordID));
Step 3: Use a simple GROUP BY query to generate the 'cloud' (by example taking the 'cloud' to mean the most common 100 tags):
with cte as (
SELECT TOP 100 KeywordID, count(*) as Count
FROM CompanyKeywords
group by KeywordID
order by count(*) desc)
select k.Keyword, c.Count
from cte c
join Keyword k on c.KeywordID = k.KeywordID;
Step 4: cache the result as it changes seldom and it computes expensively.

I'd much rather see your design normalized as suggested by Remus, but if you're at a point where you can't change your design...
You can use a parsing function (the example I'll use is taken from here), to parse your keywords and count them.
CREATE FUNCTION [dbo].[fnParseStringTSQL] (#string NVARCHAR(MAX),#separator NCHAR(1))
RETURNS #parsedString TABLE (string NVARCHAR(MAX))
AS
BEGIN
DECLARE #position int
SET #position = 1
SET #string = #string + #separator
WHILE charindex(#separator,#string,#position) <> 0
BEGIN
INSERT into #parsedString
SELECT substring(#string, #position, charindex(#separator,#string,#position) - #position)
SET #position = charindex(#separator,#string,#position) + 1
END
RETURN
END
go
create table MyTest (
id int identity,
keywords nvarchar(256)
)
insert into MyTest
(keywords)
select 'sql server,oracle,db2'
union
select 'sql server,oracle'
union
select 'sql server'
select k.string, COUNT(*) as count
from MyTest mt
cross apply dbo.fnParseStringTSQL(mt.keywords,',') k
group by k.string
order by count desc
drop function dbo.fnParseStringTSQL
drop table MyTest

Both Remus and Joe are correct but yes as what Joe said if you dont have a choice then you have to live with it. I think I can offer you an easy solution by using an XML Data Type. You can already easily view the parsed column by doing this query
WITH myCommonTblExp AS (
SELECT CompanyID,
CAST('<I>' + REPLACE(Keywords, ',', '</I><I>') + '</I>' AS XML) AS Keywords
FROM Companies
)
SELECT CompanyID, RTRIM(LTRIM(ExtractedCompanyCode.X.value('.', 'VARCHAR(256)'))) AS Keywords
FROM myCommonTblExp
CROSS APPLY Keywords.nodes('//I') ExtractedCompanyCode(X)
now knowing that you can do that, all you have to do is to group them and count, but you cannot group XML methods so my suggestion is create a view of the query above
CREATE VIEW [dbo].[DissectedKeywords]
AS
WITH myCommonTblExp AS (
SELECT
CAST('<I>' + REPLACE(Keywords, ',', '</I><I>') + '</I>' AS XML) AS Keywords
FROM Companies
)
SELECT RTRIM(LTRIM(ExtractedCompanyCode.X.value('.', 'VARCHAR(256)'))) AS Keywords
FROM myCommonTblExp
CROSS APPLY Keywords.nodes('//I') ExtractedCompanyCode(X)
GO
and perform your count on that view
SELECT Keywords, COUNT(*) AS KeyWordCount FROM DissectedKeywords
GROUP BY Keywords
ORDER BY Keywords
Anyways here is the full article -->http://anyrest.wordpress.com/2010/08/13/converting-parsing-delimited-string-column-in-sql-to-rows/