We Keep Coding

function set table name as parameter and get columns name and table name from XML file in sqlcommand c# [duplicate]

Here is my SQL query below. I want to select values from the column names given as variables. Is there any appropriate way of doing this except using a dynamic query?
SELECT EPV.EmployeeCode, #RateOfEmployee, #RateOfEmployer
FROM [HR_EmployeeProvisions] EPV

One way to do this without using dynamic sql is using CASE statement
But this is ugly
SELECT EPV.EmployeeCode, case #RateOfEmployee when 'RateOfEmployee' then RateOfEmployee
when 'X' then X
..
end , case #RateOfEmployer when 'RateOfEmployer' then RateOfEmployer
when 'Y' then Y
..
end
FROM [HR_EmployeeProvisions] EPV
You have to check all the column's in CASE statement.

You can't parameterize identifiers in Sql server, and I doubt it's possible in any other relational database.
Your best choice is to use dynamic Sql.
Note that dynamic sql is very often a security hazard and you must defend your code from sql injection attacks.
I would probably do something like this:
Declare #Sql nvarchar(500)
Declare numberOfColumns int;
select #numberOfColumns = count(1)
from information_schema.columns
where table_name = 'HR_EmployeeProvisions'
and column_name IN(#RateOfEmployee, #RateOfEmployer)
if #numberOfColumns = 2 begin
Select #Sql = 'SELECT EmployeeCode, '+ QUOTENAME(#RateOfEmployee) +' ,'+ QUOTENAME(#RateOfEmployer) +
'FROM HR_EmployeeProvisions'
exec(#Sql)
end
This way you make sure that the column names actually exists in the table, as well as using QUOTENAME as another layer of safety.
Note: in your presentation layer you should handle the option that the select will not be performed since the column names are invalid.

Have a look at UNPIVOT clause - I'm not sure it is applicable for your case but in some circumstances it can be used to query a value by the column name without dynamic SQL:
create table t1 (
a int,
b int,
c int
);
insert into t1 values
(1, 11, 111),
(2, 22, 222),
(3, 33, 333);
select a, col_name, col_value from t1
unpivot (col_value for col_name in (b, c)) as dt;
Result:
| a | col_name | col_value |
|---|----------|-----------|
| 1 | b | 11 |
| 1 | c | 111 |
| 2 | b | 22 |
| 2 | c | 222 |
| 3 | b | 33 |
| 3 | c | 333 |
(SQL Fiddle)
If you only need a value in a depending on some condition on (dynamically) either b or c, you can build the condition on that. If you need either values in column b or c, you can add ... WHERE col_name = ?. If you need more columns, you'd probably need to filter the column values on the un-pivoted table than pivot it again to get the values back in columns.

how to show remaining data by comparing another table

Table 1: ABC table 2: PQR
code|Name|Amount code|Name|Amount
----+----+----- ----+----+------
1 | A | 1000 1 | A | 1000
2 | B | 2000 2 | B | 2000
3 | C | 4000
4 | D | 1000
data in table 2 is insert from data based on table 1, now by pressing a button named "Remaining" i want to show data that is not present in table 2, to know which tuples i have missed to fill from table 1. How can i do it?

If the fields in the 2 tables are exactly the same and in the same order?
But you can't bother to put those fields in the SQL?
Then you could also use an EXCEPT
SELECT * FROM ABC
EXCEPT
SELECT * FROM PQR;
And if you're not certain that the fields are in the same order?
Then list them in the SQL.
That has also the benefit that the SQL will probably still work when one of the tables is altered.
SELECT [code], [Name], [Amount] from ABC
EXCEPT
SELECT [code], [Name], [Amount] FROM PQR;
It filters out the PQR records that are exactly the same as those found in ABC.
But normally, the methods that Tim Biegeleisen showed are more commonly used.

This answer assumes that you want to find all records in the first table which are not already present in the second table. One option uses a left join:
SELECT t1.*
FROM ABC t1
LEFT JOIN PQR t2
ON t1.code = t2.code AND t1.Name = t2.Name AND t1.Amount = t2.Amount
WHERE t2.code IS NULL;
We could also phrase this using EXISTS:
SELECT t1.*
FROM ABC t1
WHERE NOT EXISTS (SELECT 1 FROM PQR t2
WHERE t1.code = t2.code AND t1.Name = t2.Name AND
t1.Amount = t2.Amount);

Update table column based on comparison of columns from 2 table (SQL)

I have the following tables.
Table 1
Id | Values | Counts
1 | rock | 0
2 | tina | 0
3 | alex | 0
Table 2
Id | Values
1 | rock
2 | alex
3 | alex
4 | rock
5 | rock
6 | tina
As you can see, table 1 contains Values as rock, tina and alex. These column will always have unique values. Counts column should check the count of 'rock' in Table 2 and update it in Counts column. for e.g. rock is shown 3 times in table 2. The counts for rock should be then 3.
Similarly for other values. Can someone pls let me know how can i achieve this using SQL. Here is how the final table should look like.
Table 1
Id | Values | Counts
1 | rock | 3
2 | tina | 1
3 | alex | 2
Any help is appreciated. I searched online and couldnot find a possible solution for this scenario.

You can generally use a JOIN between 2 tables to update Table1 with values from Table2 (or further if you are using bridge tables).
UPDATE t1
SET t1.dataColumn = t2.dataColumn
FROM Table1 t1
INNER JOIN Table2 t2 ON t1.keyColumn = t2.keyColumn
However, when you are using Aggregate functions (such as Count, Sum)you must utilize a subquery for the second table and perform the JOIN to that subquery
UPDATE t1
SET t1.Counts = sb.Counts
FROM Table1 AS t1
INNER JOIN (
SELECT [values], Counts = Count([values])
FROM Table2
GROUP BY [values]
) AS sb
ON t1.[values] = sb.[values]
Running this on your tables gave me this:
SELECT * FROM Table1
id values counts
---- ------- -------
1 rock 3
2 tina 1
3 alex 2
One thing concerning your table design; I generally recommend not using reserved/special/key words when naming tables, columns, or other database objects. I also try to avoid using the generic name id because it can get confusing when you start linking tables to one another, even idTable1 can make things a lot easier

In SQL Server, using a correlated subquery:
update t1
set t1.Counts = (
select count(*)
from t2
where t2.[Values] = t1.[Values]
);
rextester demo: http://rextester.com/SBYNB72372
In MySQL, using a correlated subquery:
update t1
set t1.Counts = (
select count(*)
from t2
where t2.`Values` = t1.`Values`
);
rextester demo: http://rextester.com/DDDC21719
Although this sort of thing might be better calculated in a view instead of stored in the t1 table.
In SQL Server:
create view dbo.t1_with_counts as
select t1.Id, t1.[Values], count(t2.[Values]) as Counts
from t1
left join t2
on t1.[Values] = t2.[Values]
group by t1.Id, t1.[Values]
go
select *
from dbo.t1_with_counts;
In MySQL:
create view t1_with_counts as
select t1.Id, t1.`Values`, count(t2.`Values`) as Counts
from t1
left join t2
on t1.`Values` = t2.`Values`
group by t1.Id, t1.`Values`;
select *
from t1_with_counts;

I would question the wisdom of keeping track of a count in a table like that. That leads to poor relational database structure and management. Instead, I suggest you remove the count column from Table 1. Then, whenever you need to see the counts you use a view:
SELECT t1.ID, t1.VALUES, COUNT(t2.ID) AS VALUE_COUNT
FROM TABLE1 t1 LEFT JOIN TABLE2 t2 ON t1.VALUES = t2.VALUES
This results in a dynamically updated view of your data instead of a static view that has the potential for going stale without your realizing it.

Monthly Report - SQL

I have the table below, how would I select in SQL the last date of each month (from the list) in each categoryID?
I want to end up with something in the line off:
CategoryID | Current | Date
1 | 5 | 2016-09-30
1 | 3 | 2016-10-30
1 | 7 | 2016-11-30
1 | 2 | 2016-12-30
etc. as history builds up.
Image :

There are a few ways to approaches to do this, one of them could be using windowing function rownumber. Within the CTE (WITH) you get local order of the records within date(using covert to get rid of the time here)+CategoryID partition by datetime DESC (-> first is latest). You need to do this because you cannot use windowing functions in WHERE clause. Then, in the main query, you actually use this CTE as your source table and get only the latest record per partition.
WITH LocallyOrdered AS (
SELECT CategoryID,
StockCurrent,
ROW_NUMBER() OVER (
PARTITION BY CategoryID, CONVERT(date, RecordAdded)
ORDER BY RecordAdded DESC)
AS RowNumberOneIsLatest
FROM OriginalTable)
SELECT CategoryID, StockCurrent FROM LocallyOrdered WHERE RowNumberOneIsLatest = 1

Considering you're using MySQL, since you haven't mentioned.
Suppose this is your table named : 'Dummy'
cat_id current date
------ ------- --------
1 5 2016-09-30
1 3 2016-10-30
1 7 2016-11-30
1 2 2016-12-30
2 4 2016-10-31
2 6 2016-10-04
Executing this query :
select
o.cat_id,
(SELECT DISTINCT
a.date
from
Dummy a
where a.cat_id = o.cat_id
ORDER BY date DESC
LIMIT 1) as 'date'
from
Dummy o
group by o.cat_id ;
Gives you the Latest date of each category :
cat_id date
------ ------------
1 2016-12-30
2 2016-10-31
EDIT
This is supposed to work specifically for your table. Just replace "yourTable" with the table's actual name.
select
o.CategoryID,
o.StockCurrent
(SELECT DISTINCT
a.RecordAdded
from
yourTable a
where a.CategoryID = o.CategoryID
ORDER BY RecordAdded DESC
LIMIT 1) as 'RecordAdded'
from
yourTable o
group by o.CategoryID ;
EDIT 2 :
This Query returns the latest date of each month within a certain category. Hope this is what you want.
SELECT
o.CategoryID,
o.StockCurrent,
o.RecordAdded
FROM
`yourTable` o
WHERE o.RecordAdded IN
(SELECT
MAX(i.RecordAdded)
FROM
`yourTable` i
GROUP BY MONTH(i.RecordAdded))
GROUP BY o.CategoryID,
o.RecordAdded ;
Suppose the table contains the following sample data:
CategoryID StockCurrent RecordAdded
---------- ------------ -------------
1 5 2016-09-01
1 3 2016-09-02
1 7 2016-10-01
1 2 2016-10-02
2 4 2016-09-01
2 6 2016-09-02
2 66 2016-10-01
2 77 2016-10-02
Running this query returns the following result set :
CategoryID StockCurrent RecordAdded
---------- ------------ -------------
1 3 2016-09-02
1 2 2016-10-02
2 6 2016-09-02
2 77 2016-10-02

try this:
WITH Temp As
(
select CategoryId, [Current], RecordAdded,
Dense_Rank() over( partition by CategoryId order by RecordAdded desc) as CatergoryWiseRank
from tblCategory
)
select CategoryId, [Current], RecordAdded from Temp where CatergoryWiseRank=1

SELECT
CASE MONTH(date_field)
WHEN 1 THEN 'Enero'
WHEN 2 THEN 'Febrero'
WHEN 3 THEN 'Marzo'
WHEN 4 THEN 'Abril'
WHEN 5 THEN 'Mayo'
WHEN 6 THEN 'Junio'
WHEN 7 THEN 'Julio'
WHEN 8 THEN 'Agosto'
WHEN 9 THEN 'Septiembre'
WHEN 10 THEN 'Octubre'
WHEN 11 THEN 'Noviembre'
WHEN 12 THEN 'Diciembre'
END as Mes, COUNT(date_field) as cantidad FROM nacimientos
WHERE YEAR(date_field)='1991'
GROUP BY MONTH(date_field)asc
Result

GroupBy Count With Subsonic 3

I like to perform the following with SubSonic 3 without using Linq (using dynamic lookup of columns and tables). Also, no inline sql (to prevent sql-injections).
http://www.java2s.com/Code/SQL/Select-Clause/COUNTandGROUPBY.htm
mysql> SELECT species, COUNT(*) FROM Bird GROUP BY species;
+---------+----------+
| species | COUNT(*) |
+---------+----------+
| Bus | 2 |
| Car | 1 |
+---------+----------+
2 rows in set (0.00 sec)
Drop table Bird;
CREATE TABLE Bird (
name VARCHAR(20),
owner VARCHAR(20),
species VARCHAR(20),
sex CHAR(1),
birth DATE,
death DATE
);
INSERT INTO Bird VALUES ('BlueBird','Joe','Car','f','1999-03-30',NULL);
INSERT INTO Bird VALUES ('RedBird','Yin','Bus','m','1979-04-30',1998-01-30);
INSERT INTO Bird VALUES ('RedBird','Yin','Bus','m','1998-01-30',NULL);
/* COUNT() and GROUP BY
Number of animals per species:
*/
SELECT species, COUNT(*) FROM Bird GROUP BY species;

You almost did it:
Try This:
SELECT species, COUNT() FROM Bird GROUP BY species;
This Work in SQL and i think it works in MySql