I want that its name would be the page address. For example, if page has heading "Some Page", than its address should be http://somesite/some_page/.
"some_page"-name generated by system automatically. "some_page" - is the unique identifier of page. The problem in that the user in the future can enter a name which already exists that will cause an error.
It is necessary to find an optimum variant of the decision of a problem for great volumes of the data.
I have solved a problem as follows:
The page identifier in a database is the name of page and a suffix which is by default equal to zero. At page addition there is a check on existence. If such page does not exist, the suffix is equal 0 and its name is "some_page", if page is exist, than - search for the maximum number of a suffix and suffix=suffix+1 and page name become "some_page_1".
For this I create in a database the compound key from fields "suffix" and "pageName":
Table Pages
suffix|pageName |pageTitle
0 |some_page |Some Page
1 |some_page |Some Page
0 |other_page|Other Page
Addition of pages occurs through stored procedure:
CREATE PROCEDURE addPage (pageNameVal VARCHAR(100), pageTitleVal VARCHAR(100))
BEGIN
DECLARE v INT DEFAULT 0;
SELECT MAX(suffix) FROM pages WHERE pageName=pageNameVal INTO v;
IF v >= 0 THEN
SET v = v + 1;
ELSE
SET v = 0;
END IF;
INSERT INTO pages (suffix, pageName) VALUES (pageNameVal, v, pageTitleVal);
END;
Whether there are more the best decisions?
I think this should be okay - it would keep multiple instances of the key distinct. However, why not use a generated key instead of something provided by the user? If you maintain control over the page's lookup ID, you'll ensure no duplicates. Your current setup shouldn't cause any trouble, though.
The only problem (though it seems highly unlikely), is that your SP has a chance to duplicate the suffix for a particular key if two callers try to save the same key at the same time - ie, two simultaniousrequests with the same brand new pagename could both end up trying to use suffix 0. If you don't care about the result of your insert statement (and your current SP doesn't return it), then just do it in a single statement inside your SP:
CREATE PROCEDURE addPage (pageNameVal VARCHAR(100), pageTitleVal VARCHAR(100))
BEGIN
INSERT INTO pages (pageName, suffix, pageTitle)
SELECT n.pageNameVal, ISNULL(NextValue, 0), n.pageTitleVal
FROM (SELECT pageNameVal, pageTitleVal) n
LEFT
JOIN (SELECT MAX(suffix+1) as NextValue FROM pages WHERE pageName=pageNameVal) m
END
Related
We have a table that has reference numbers for documents. The simplified version of this table, call it RefNum, is,
id - int - identity
refN - smallint - the reference number
avail - bit - is number available (0 - is available, 1 - not available)
This table is pre-filled with refN's that have avail = 0. The reference number is available if avail is zero.
How do I write the SQL to select the next available reference number, and update it(set avail to 1), without worrying about two users getting the same number?
Can I simply wrap the SQL statements in a BEGIN / COMMIT TRANSACTION block?
I'm sure I'm over thinking this.
Thanks in advance.
I would also recommend a sequence but if you really have to use what is there then the following should work:
DECLARE #op TABLE (RefN smallint NOT NULL);
UPDATE RefNums
SET avail = 1
OUTPUT inserted.RefN
INTO #op
WHERE RefN =
(
SELECT MIN(RefN)
FROM RefNums WITH (UPDLOCK)
WHERE avail = 0
);
SELECT *
FROM #op;
use sequence for Ref number & user sequence for update
check below URL
Link : https://www.c-sharpcorner.com/blogs/create-sequence-in-sql
Sequence generate Unique number every time
I have a problem to resolve cache updates when delta includes fields that have UNIQUE constraint on the database. I have a database with the following DDL schema (SQLite in memory can be used to reproduce):
create table FOO
(
ID integer primary key,
DESC char(2) UNIQUE
);
The initial database table contains one record with ID = 1 and DESC = R1
Acessing this table with a TFDQuery (select * from FOO), if the following steps are performed, the generated delta will be correctly applied with ApplyUpdates:
Update record ID = 1 to DESC = R2
Append a new record ID = 2 with DESC = R1
Delta includes the following:
R2
R1
No error will be generated on ApplyUpdates, because the first operation on delta will be an update. The second will be an insert. As record 1 now is R2, the insertion can be done because there are no violation of the unique contraint on this transaction.
Now, performing the following steps, will generate the exactly same delta (look at the FDQuery.Delta property), but a UNIQUE constraint violation will be generated.
Append a new temporary record ID = 2 with DESC = TT
Update the first record ID = 1 to DESC = R2
Update the temporary record 2 - TT to DESC = R1
Delta includes the following:
R2
R1
Note that FireDAC generates the same delta on both scenarios, this can be viewed through the FDquery's Delta property.
This steps cand be used to reproduce the error:
File > New VCL Forms Application; Drop a FDConnection and FDQuery on form; Set FDConnection to use SQLite driver (using in memory database); Drop two buttons on form, one to reproduce the correctly behavior, and another to reproduce the error, as follows:
Button OK:
procedure TFrmMain.btnOkClick(Sender: TObject);
begin
// create the default database with a FOO table
con.Open();
con.ExecSQL('create table FOO' + '(ID integer primary key, DESC char(2) UNIQUE)');
// insert a default record
con.ExecSQL('insert into FOO values (1,''R1'')');
qry.CachedUpdates := true;
qry.Open('select * from FOO');
// update the first record to T2
qry.First();
qry.Edit();
qry.Fields[1].AsString := 'R2';
qry.Post();
// append the second record to T1
qry.Append();
qry.Fields[0].AsInteger := 2;
qry.Fields[1].AsString := 'R1';
qry.Post();
// apply will not generate a unique constraint violation
qry.ApplyUpdates();
end;
Button Error:
// create the default database with a FOO table
con.Open();
con.ExecSQL('create table FOO' + '(ID integer primary key, DESC char(2) UNIQUE)');
// insert a default record
con.ExecSQL('insert into FOO values (1,''R1'')');
qry.CachedUpdates := true;
qry.Open('select * from FOO');
// append a temporary record (TT)
qry.Append();
qry.Fields[0].AsInteger := 2;
qry.Fields[1].AsString := 'TT';
qry.Post();
// update R1 to R2
qry.First();
qry.Edit();
qry.Fields[1].AsString := 'R2';
qry.Post();
qry.Next();
// update TT to R1
qry.Edit();
qry.Fields[1].AsString := 'R1';
qry.Post();
// apply will generate a unique contraint violation
qry.ApplyUpdates();
Update Since writing the original version of this answer, I've done some more investigation and am beginning to think that either there is a problem with ApplyUpdates, etc, in FireDAC's support for Sqlite (in Seattle, at least), or we are not using the FD components correctly. It would need FireDAC's author (who is a contributor here) to say which it is.
Leaving aside the ApplyUpdates business for a moment, there are a number of other problems with your code, namely your dataset navigation makes assumptions about the ordering on the rows in qry and the numbering of its Fields.
The test case I have used is to start (before execution of the application) with the Foo table containing the single row
(1, 'R1')
Then, I execute the following Delphi code, at the same time as monitoring the contents of Foo using an external application (the Sqlite Manager plug-in for FireFox). The code executes without an error being reported in the application, but notice that it does not call ApplyUpdates.
Con.Open();
Con.StartTransaction;
qry.Open('select * from FOO');
qry.InsertRecord([2, 'TT']);
assert(qry.Locate('ID', 1, []));
qry.Edit;
qry.FieldByName('DESC').AsString := 'R2';
qry.Post;
assert(qry.Locate('ID', 2, []));
qry.Edit;
qry.FieldByName('DESC').AsString := 'R1';
qry.Post;
Con.Commit;
qry.Close;
Con.Close;
The added row (ID = 2) is not visible to the external application until after Con.Close has executed, which I find puzzling. Once Con.Close has been called, the external application shows Foo as containing
(1, 'R2')
(2, 'R1')
However, I have been unable to avoid the constraint violation error if I call ApplyUpdates, regardless of any other changes I make to the code, including adding a call to ApplyUpdates after the first Post.
So, it seems to me that either the operation of ApplyUpdates is flawed or it is not being used correctly.
I mentioned FireDAC's author. His name is Dmitry Arefiev and he has answered a lot of FD qs on SO, though I haven't noticed him here in the past couple of months or so. You might try catching his attention by posting in EMBA's FireDAC NG forum, https://forums.embarcadero.com/forum.jspa?forumID=502.
I need some help from a MS SQL Master...
Short version:
When I execute a Conditional Where followed by a Contains, my query delays 1 minute (In its normal execution, it takes 200 milliseconds).
With this query, everything works fine:
Where
Contains(table.product_name, #search_word)
But with a Conditional Where, it takes 1 minute to execute:
Where
(#ExecuteWhereStatement = 0 Or (Contains(table.product_name, #search_word))
Long Version:
I'm using a stored procedure that receives some parameters. This Stored Procedure query a really large table, but everything is indexed properly and the query goes very well so far.
The main query is a little big, so I want to make the WHERE clause more smart possible, to avoid repeat multiple times the same statement.
The whole idea of the DataBase, is a history of purchases made by the State. So this query involves 3 tables:
Table 1 (table_purchase) - The purchase itself
id_purchase int (PK)
date_purchase datetime
buyer_code int (Nullable)
Table 2 (table_purchase_product) - The Items of a Purchase
id_product int (PK)
id_purchase int (FK of table_purchase)
product_quantity int (Nullable)
product_name varchar(255) (Nullable) (Full-Text-Indexed)
product_description varchar(2000) (Nullable) (Full-Text-Indexed)
id_product_bid_winner int (FK of table_product_bid)
Table 3 (table_product_bids) - The Bids for Each product of a Purchase
id_product_bid int (PK)
id_product int (FK of table_purchase_product)
product_brand varchar(255) (Nullable) (Full-Text-Indexed)
bid_value decimal (20,6)
So basicly, We have a "Purchase", that has several "Products (or Items)", and each "Product" has some "Bids (or Prices)"
And there is the Bad Girl (The SQL Stored Procedure):
ALTER PROCEDURE [dbo].[procPesquisaFullText]
#search_date datetime,
#search_word varchar(8000),
#search_brand varchar(255),
#only_one_bid bit = 0,
#search_buyer_code int = 0,
#quantityFrom decimal(20,6) = 0,
#quantityTo decimal(20,6) = 0
AS
BEGIN
SET NOCOUNT ON;
Declare #ExecuteWordSearch AS bit;
if (#uasg != 0 And #search_word = '')
begin
Set #ExecuteWordSearch = 0;
Set #search_word = 'nothing';
end
else
begin
Set #ExecuteWordSearch = 1;
end
Declare #ExecuteBrandSearch AS bit;
if (#search_brand = '')
begin
Set #ExecuteBrandSearch = 0;
Set #search_brand = 'nothing';
end
else
begin
Set #ExecuteMarcaSearch = 1;
end
begin
SELECT
pp.id_product,
pp.id_purchase,
pp.description
FROM
table_purchase_product pp
inner join table_purchase p on p.id_purchase = pp.id_purchase
WHERE
(p.date_purchase >= #search_date)
and (#search_buyer_code = 0 or (l.buyer_code = #search_buyer_code))
and (#quantityFrom = 0 or (li.product_quantity >= #QuantityFrom))
and (#quantityTo = 0 or (li.product_quantity <= #QuantityTo))
and (contains(pp.product_description, #search_word) or contains(pp.product_name, #search_word))
and (#only_one_bid = 0
or ((Select COUNT(*) From table_product_bid Where table_product_bid.id_product = pp.id_product) = 1))
and (#ExecuteBrandSearch = 0 Or (exists(
select 1
from table_product_bid ppb
where ppb.id_product_bid = pp.id_product_bid_winner
and contains(ppb.product_brand, #search_brand)
)
))
ORDER BY p.date_purchase DESC
end
END
So far, so good...
In the beginning I set two variables, used inside the query.
The first, verify if the user specified a "Buyer Code" AND didn't specify a "Search Word" (So, not the Product's description nor the Product's name is verified)
The second, verify if the user specified a "Specific Brand". If so, then the Winning Bid's BRAND is verified to match the users one.
Observation: You'll notice that when the "Search Words" is empty, I set them to "nothing". I do it because if the search term in the Contains is empty, it throws me a exception, even when it's not executed (I tested it in another query, absolutely isolated too)
As You can see, my user is able to search for:
- "Products" of Some Distinct Buyer "Purchase" (passing the #search_buyer_code parameter)
- A "Product" that contains a distinct word in its name or description
- A "Product" that has the Winner Bid of a specific Brand
- A "Product" that has only 1 bid at all
- A "Product" with a maximum and minimum quantity
And You'll notice that I used a lot of Conditions INSIDE the Where, producing a very dynamic Where, instead of using a "BIG If Else" statement, and repeating a lot of code. (I guess some "Googlers" will land here looking for Conditionally Wheres, and If so, I'm glad to help!)
Ok, so everything works veeery great at all. The query executes flawless. But here is the strange, damn, tricky issue:
If I want the user to be able to specify only a "Buyer Code" for Purchase, but No Word to Search of the Product using the code above (which is the first piece of code in the stored procedure does):
Changing from:
and (contains(pp.product_description, #search_word) or contains(pp.product_name, #search_word))
To:
and (#ExecuteWordSearch = 0 Or (contains(pp.product_description, #search_word) or contains(pp.product_name, #search_word)))
The query delays near 1 minute! (the execution is about 200 milliseconds for the query above).
But WHY??? I Use the same Logic of in all "Conditionally Wheres". I also use the same logic of having a flag/variable to indicate when execute the Where clause in the Word Search and the Brand Search, but the Brand Search works PERFECTLY! So Why, WHY only when I use the condition followed by a Contains my query delays 1 minute????
And this issue is not related with the amount of data, because I tried removing the entire Contains condition, allowing a lot of data to return, and it takes 1 second maximum...
Ow, It's a Microsoft SQL Server 2008 R2.
Thanks already for You read so far!
I cannot find the documentation I had around a very similar issue, but it sounded so familiar, I at least wanted to share what I remembered. Part of the issue is that for Sql Server, the full-text search engine is separate from the regular query execution engine, and so when you mix the two, in some cases, performance can tank. This is particularly true when the condition is an 'OR' rather than and 'AND'. (I remember hitting this exact situation). Conditional ANDs worked fine. But for OR, it's as if each condition gets evaluated repeatedly row by row.
Among the workarounds, one is, as already suggested, create your sql dynamically before execution.
Another would be to break the full-text and non-full text conditions into two search functions (literally UDF's) and then do whatever is needed (INTERSECT, EXCEPT, etc) with the two resultsets.
Try changing your WHERE clause to use a CASE statement, e.g.:
WHERE
CASE
WHEN #ExecuteWhereStatement = 0 THEN 1
WHEN #ExecuteWhereStatement = 1 THEN
CASE
WHEN CONTAINS([table].product_name, #search_word) THEN 1
ELSE 0
END
END = 1;
I m trying to write if statement to give error message if user try to add existing ID number.When i try to enter existing id i get error .untill here it s ok but when i type another id no and fill the fields(name,adress etc) it doesnt go to database.
METHOD add_employee.
DATA: IT_EMP TYPE TABLE OF ZEMPLOYEE_20.
DATA:WA_EMP TYPE ZEMPLOYEE_20.
Data: l_count type i value '2'.
SELECT * FROM ZEMPLOYEE_20 INTO TABLE IT_EMP.
LOOP AT IT_EMP INTO WA_EMP.
IF wa_emp-EMPLOYEE_ID eq pa_id.
l_count = l_count * '0'.
else.
l_count = l_count * '1'.
endif.
endloop.
If l_count eq '2'.
WA_EMP-EMPLOYEE_ID = C_ID.
WA_EMP-EMPLOYEE_NAME = C_NAME.
WA_EMP-EMPLOYEE_ADDRESS = C_ADD.
WA_EMP-EMPLOYEE_SALARY = C_SAL.
WA_EMP-EMPLOYEE_TYPE = C_TYPE.
APPEND wa_emp TO it_emp.
INSERT ZEMPLOYEE_20 FROM TABLE it_emp.
CALL FUNCTION 'POPUP_TO_DISPLAY_TEXT'
EXPORTING
TITEL = 'INFO'
TEXTLINE1 = 'Record Added Successfully.'.
elseif l_count eq '0'.
CALL FUNCTION 'POPUP_TO_DISPLAY_TEXT'
EXPORTING
TITEL = 'INFO'
TEXTLINE1 = 'Selected ID already in database.Please type another ID no.'.
ENDIF.
ENDMETHOD.
I'm not sure I'm getting your explanation. Why are you trying to re-insert all the existing entries back into the table? You're just trying to insert C_ID etc if it doesn't exist yet? Why do you need all the existing entries for that?
If so, throw out that select and the loop completely, you don't need it. You have a few options...
Just read the table with your single entry
SELECT SINGLE * FROM ztable INTO wa WITH KEY ID = C_ID etc.
IF SY-SUBRC = 0.
"this entry exists. popup!
ENDIF.
Use a modify statement
This will overwrite duplicate entries with new data (so non key fields may change this way), it wont fail. No need for a popup.
MODIFY ztable FROM wa.
Catch the SQL exceptions instead of making it dump
If the update fails because of an exception, you can always catch it and deal with exceptional situations.
TRY .
INSERT ztable FROM wa.
CATCH sapsql_array_insert_duprec.
"do your popup, the update failed because of duplicate records
ENDTRY.
I think there's a bug when appending in internal table 'IT_EMP' and inserting in 'ZEMPLOYEE_20' table.
Suppose you append the first time and then you insert. But when you append the second time you will have 2 records in 'IT_EMP' that are going to be inserted in 'ZEMPLOYEE_20'. That is because you don't refresh or clear the internal table and there you will have a runtime error.
According to SAP documentation on 'Inserting Lines into Tables ':
Inserting Several Lines
To insert several lines into a database table, use the following:
INSERT FROM TABLE [ACCEPTING DUPLICATE KEYS] . This
writes all lines of the internal table to the database table in
one single operation. The same rules apply to the line type of
as to the work area described above. If the system is able to
insert all of the lines from the internal table, SY-SUBRC is set to 0.
If one or more lines cannot be inserted because the database already
contains a line with the same primary key, a runtime error occurs.
Maybe the right direction here is trying to insert the work area directly but before you must check if record already exists using the primary key.
Check the SAP documentation on this issue clicking the link before.
On the other hand, once l_count is zero because of l_count = l_count * '0'. that value will never change to any other number making that you won't append or insert again.
why are you retrieving all entries from zemployee_20 ?
You can directly check wether the 'id' exists already or not by using select single. If exists, then show message, if not, add.
It is recommended to retrieve only one field when its needed and not the entire table with asterisc *
SELECT single employee_id FROM ZEMPLOYEE_20 where employee_id = p_id INTO v_id. ( or field in structure )
if sy-subrc = 0. "exists
"show message
else. "not existing id
"populate structure and then add record to Z table
endif.
Furthermore, l_count is not only unnecessary but also bad implemented.
You can directly use the insert query,if the sy-subrc is unsuccessful raise the error message.
WA_EMP-EMPLOYEE_ID = C_ID.
WA_EMP-EMPLOYEE_NAME = C_NAME.
WA_EMP-EMPLOYEE_ADDRESS = C_ADD.
WA_EMP-EMPLOYEE_SALARY = C_SAL.
WA_EMP-EMPLOYEE_TYPE = C_TYPE.
INSERT ZEMPLOYEE_20 FROM WA_EMP.
If sy-subrc <> 0.
Raise the Exception.
Endif.
I am not much strong in SQL, so looking for some help.
First I am looking for suggestion for the best way to implement this logic in SQL and then some sample code to implement.
My portal is going to connect Students and Training Providers.
Students: Select what courses (multiple) they want, type of delivery (online, class room), Industry(domain) to which the course to be targeted more, Location Preference.
Training Providers: Select what courses offering (so one record for each course), offering locations, type of delivery for each course, industries (multiple) it is targeting.
When student login:
I would like to create SP which in turn create view to store the matched records of the Training Providers data which matches that student needs of that StudentID, CourseID passed to SP
I have created the following sp ( but not included create view part as I am not sure how to do this)
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
ALTER PROCEDURE [dbo].[sp_TPsMatched2StuCourse]
-- Add the parameters for the stored procedure here
#StuID int,
#CourseID int
AS
BEGIN
Select TP.MemID,TP.PastExp,SN.DeliveryType,SN.LocPref,SN.Industry,SC.CourseID from
tbl_TrainingProvider as TP , tbl_StuCourses as SC, tbl_StuNeeds SN
where SN.CourseID = #CourseID and SN.StuID = #StuID and
SN.DeliveryType in (TP.DeliveryMode) and
SN.LocPref IN (TP.LocOffering) and
SN.Industry IN (TP.Industries)
END
--- exec sp_ELsMatched2EntProp 1, 1
Why I need to put the data is as follows:
Assume the data is stored in that dynamic view and that would be bind to datagrid. Student then select interested TPs. Then only contact details would be shared to each other and this cannot be reveresed. So I would put this interested data in another table later. Every time data changes, hence the matches. Student can change some of his/her needs or new TPs join etc so view to be temparory.
when I executed this using above command, I am not getting data though it matches few records. What is wrong I am doing.
Any help would be greatly appreciated.
You are not getting expected results because you filter out too many records in WHERE( I'm talking about this part : SN.DeliveryType in (TP.DeliveryMode) and
SN.LocPref IN (TP.LocOffering) and SN.Industry IN (TP.Industries)). I'd recommend to use JOIN ... ON instead of specifying all tables in FROM and join condition in WHERE. I'm not sure what you want exactly, but I believe you are looking for
FROM tbl_StuNeeds SN
LEFT JOIN tbl_TrainingProvider as TP ON (TP.DeliveryMode = SN.DeliveryType AND
SN.LocPref = TP.LocOffering AND TP.Industries = SN.Industry)
WHERE SN.CourseID = #CourseID and SN.StuID = #StuID
Also, there is no join conditions in your code for tbl_StuCourses as SC which results in cross-join.
Finally, why do you need a stored procedure at all? From what I see in your example, a table-valued function will work better:
CREATE FUNCTION [dbo].getTPsMatched2StuCourse(#StuID INT,#CourseID INT)
RETURNS TABLE AS
RETURN
Select .... ;