MYSQL syntax for if with data stored in the database - mariadb

i want to create in mysql an event schedule every day that check
if the current date is greater than a date stored in the database table and then call some store procedures.
Reading my WRONG mysql code you will understand that i want to do:
delimiter $
set global event_scheduler = on$
create event if not exists `end_qualifications`
on schedule
every day
do
begin
if curdate() >= (select `end_date` from `round` where `nome` =
"qualifications")
then
/* call myprocedure(params); */
end if;
end $
delimiter ;
I found here If-statement in the MySQL stored procedure for selecting data something similar, but there is not way my code work as i want.
I'm a beginner with mysql so it's possible that what i want to do can't be done.
Anyone knows how to make my code work?
I'm using MySQL client version: 5.7.25
EDITED: this is the error i get when i try to run the query
ERROR 1064 (42000): You have an error in your SQL syntax; check the
manual that corresponds to your MariaDB server version for the right
syntax to use near 'do
begin
if curdate() >= (select `end_date` from `round` where `nome` =
"q' at line 5
I don't know if it matters, but the database is empty for now.

Related

How to execute MariaDB stored procedure from azure data factory?

I wanted to 'Call' MariaDB Procedure from Azure Data Factory.
How can this be achieved, are there any other service which can be integrated with ADF to call this MariaDB procedures
I tried calling the procedure by writing the query using lookup activity.
It fails while showing this error.
ErrorCode=InvalidParameter,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=The value of the property 'columns' is invalid: 'Value cannot be null.
Parameter name: columns'.,Source=,''Type=System.ArgumentNullException,Message=Value cannot be null.
Parameter name: columns,Source=Microsoft.DataTransfer.Common,'
Lookup activity reads and returns the content of the query. I tried to repro this by creating three stored procedures in Azure SQL database for Maria DB.
First Stored procedure is written to update the data in the table.
DELIMITER $$
CREATE PROCEDURE update_inventory()
BEGIN
UPDATE inventory SET quantity = 150
WHERE id = 1;
END$$
DELIMITER ;
When this procedure is called in ADF lookup activity, error occurs.
Second stored procedure is written with select query.
DELIMITER $$
CREATE PROCEDURE select_inventory()
BEGIN
select * from inventory;
END$$
DELIMITER ;
When this SP is called, ADF pipeline is executed successfully.
In order to execute the stored procedure with update statements (or any statements), a select statement is added in the Stored procedure.
DELIMITER $$
CREATE PROCEDURE update_select_inventory()
BEGIN
UPDATE inventory SET quantity = 150
WHERE id = 1;
select * from inventory;
END$$
DELIMITER ;
When this stored procedure is called through Lookup activity, it got executed successfully.
Try adding select statement in the stored procedure and execute it in Lookup activity. Or add Select statement after Call stored procedure statement.
By selecting the 'query' option, you can call the stored procedure using lookup activity. From your error message, it looks like you are missing the parameter columns while calling the stored procedure.
Did you try executing the same code using the client tools like MySQL workbench? If you can execute the stored proc from other client tools, then you should be able to execute the same using the lookup activity.
I tested from my end and was able to execute the Stored procedure using lookup activity. Please see the below screenshot for your reference.

sql not a valid month error in sql command line

Actually I was trying to get all columns within a date range in Oracle db and I am successful in doing so in SQL Developer but when I execute the same code in SQL command line interface I get an error
ORA-01843 : not a valid month
I know its an error which comes in to_date format but it gets executed in SQL developer as exactly I expected but not in SQL command line. Why does this happen??
select to_date('01/04/2020') from dual;
Even this command is not working.
I had tried all format methods for the to_date method conversion and I checked nls_date_format which shows 'DD-MM-RR'
I'd suggest you to always provide appropriate format mask. Don't rely on Oracle implicitly converting & guessing what you wanted to do.
String that looks like '01/04/20' could be anything, depending on format you used (dd/mm/yy, yy/dd/mm, mm/yy/dd ... all of that is valid, but only one is correct).
SQL> alter session set nls_Date_format = 'dd-mm-rr';
Session altered.
SQL> select to_date('01/04/2020', 'dd/mm/yyyy') result from dual;
RESULT
------------------------------
01-04-20
SQL>

How to write sqlite transaction that rolls back on any error

I have searched extensively on this and I have found a lot of people asking the question but no answers that included code examples to help me understand.
I'd like to write a transaction (in sql using the command line sqlite3 interface) that performs several update statements, and if any of them fail for any reason, rolls back the transaction. The default behaviour appears to be to roll-back the statement that failed but commit the others.
This tutorial appears to advise that it's sufficient to add begin; and rollback; before and after the statements, but that's not true because I've tried it with deliberate errors and the non-error statements were definitely committed (which I don't want).
This example really confuses me because the two interlocutors seem to give conflicting advice at the end - one says that you need to write error handling (without giving any examples) whereas the other says that no error handling is needed.
My MWE is as follows:
create table if not exists accounts (
id integer primary key not null,
balance decimal not null default 0
);
insert into accounts (id, balance) values (1,200),(2,300);
begin transaction;
update accounts set balance = field1 - 100 where id = 1;
update accounts set balance = field1 + 100 where id = 2;
update accounts set foo = 23; //Deliberate error
commit;
The idea is that none of these changes should be committed.
The sqlite3 command-line shell is intended to be used interactively, so it allows you to continue after an error.
To abort on the first error instead, use the -bail option:
sqlite3 -bail my.db < mwe.sql
If you are executing line by line, then the idea is that you first run these commands:
create table if not exists accounts (
id integer primary key not null,
balance decimal not null default 0
);
insert into accounts (id, balance) values (1,200),(2,300);
begin transaction;
update accounts set balance = field1 - 100 where id = 1;
update accounts set balance = field1 + 100 where id = 2;
update accounts set foo = 23; //Deliberate error
At this point, if you have no errors, you run the commit:
commit;
All the updates should be visible if you open a second connection and query the table.
On another hand if you got an error, instead of committing you rollback:
rollback;
All the updates should be rolled back;
If you are doing it programatically in java you would enclose the updates in a try - catch block, and commit at the end of the try, or rollback inside the catch.

How to create database link dynamically

I am new in oracle db...
I need to create a database link by passing link name and connection string as variable.
DECLARE DBLINK_NAME varchar(100) :='newdblink';
Connection varchar(250) := '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=host.name.com)(Port=1521))(CONNECT_DATA=(SID=host)))';
BEGIN
EXECUTE IMMEDIATE 'CREATE DATABASE LINK' ||DBLINK_NAME||
'CONNECT TO SCHEMA_NAME IDENTIFIED BY password USING '||Connection;
END;
Can any one tell me what wrong in passing this variable value in execute statement?
I am doing using TOAD and oracle 11g.
You have missed the spaces around the database link name, so your command ends up as:
CREATE DATABASE LINKnewdblinkCONNECT TO ...
which will generate an ORA-01501: CREATE DATABASE failed error. You need to include a space after LINK and before CONNECT.
Your connect string also needs to be enclosed in single quotes, so you need to concatenate those as well, and they need to be escaped:
DECLARE
DBLINK_NAME varchar(100) :='newdblink';
Connection varchar(250) := '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=host.name.com)(Port=1521))(CONNECT_DATA=(SID=host)))';
BEGIN
EXECUTE IMMEDIATE 'CREATE DATABASE LINK ' || DBLINK_NAME
|| ' CONNECT TO SCHEMA_NAME IDENTIFIED BY password USING '''
|| Connection || '''';
END;
/
PL/SQL procedure successfully completed.
It's helpful to use dbms_output to display exactly what the execute immediate will try to run. You can often spot mistakes quickly - the missing spaces would have been pretty obvious - and can copy-and-patse the generated statement to run it as plain SQL, which can sometimes make other issues more obvious.
I'm not sure what the benefit of using PL/SQL, variables and dynamic SQL is here. You can just do a simple SQL statement using those values. Perhaps you intend to turn this into a procedure. But creating a link at run-time would be unusual.

Stored procedure slow when called from web, fast from Management Studio

I have stored procedure that insanely times out every single time it's called from the web application.
I fired up the Sql Profiler and traced the calls that time out and finally found out these things:
When executed the statements from within the MS SQL Management Studio, with same arguments (in fact, I copied the procedure call from sql profile trace and ran it): It finishes in 5~6 seconds avg.
But when called from web application, it takes in excess of 30 seconds (in trace) so my webpage actually times out by then.
Apart from the fact that my web application has its own user, every thing is same (same database, connection, server etc)
I also tried running the query directly in the studio with the web application's user and it doesn't take more than 6 sec.
How do I find out what is happening?
I am assuming it has nothing to do with the fact that we use BLL > DAL layers or Table adapters as the trace clearly shows the delay is in the actual procedure. That is all I can think of.
EDIT I found out in this link that ADO.NET sets ARITHABORT to true - which is good for most of the time but sometime this happens, and the suggested work-around is to add with recompile option to the stored proc. In my case, it's not working but I suspect it's something very similar to this. Anyone knows what else ADO.NET does or where I can find the spec?
I've had a similar issue arise in the past, so I'm eager to see a resolution to this question. Aaron Bertrand's comment on the OP led to Query times out when executed from web, but super-fast when executed from SSMS, and while the question is not a duplicate, the answer may very well apply to your situation.
In essence, it sounds like SQL Server may have a corrupt cached execution plan. You're hitting the bad plan with your web server, but SSMS lands on a different plan since there is a different setting on the ARITHABORT flag (which would otherwise have no impact on your particular query/stored proc).
See ADO.NET calling T-SQL Stored Procedure causes a SqlTimeoutException for another example, with a more complete explanation and resolution.
I also experience that queries were running slowly from the web and fast in SSMS and I eventually found out that the problem was something called parameter sniffing.
The fix for me was to change all the parameters that are used in the sproc to local variables.
eg. change:
ALTER PROCEDURE [dbo].[sproc]
#param1 int,
AS
SELECT * FROM Table WHERE ID = #param1
to:
ALTER PROCEDURE [dbo].[sproc]
#param1 int,
AS
DECLARE #param1a int
SET #param1a = #param1
SELECT * FROM Table WHERE ID = #param1a
Seems strange, but it fixed my problem.
Not to spam, but as a hopefully helpful solution for others, our system saw a high degree of timeouts.
I tried setting the stored procedure to be recompiled by using sp_recompile and this resolved the issue for the one SP.
Ultimately there were a larger number of SP's that were timing-out, many of which had never done so before, by using DBCC DROPCLEANBUFFERS and DBCC FREEPROCCACHE the incident rate of timeouts has plummeted significantly - there are still isolated occurrences, some where I suspect the plan regeneration is taking a while, and some where the SPs are genuinely under-performant and need re-evaluation.
Could it be that some other DB calls made before the web application calls the SP is keeping a transaction open? That could be a reason for this SP to wait when called by the web application. I say isolate the call in the web application (put it on a new page) to ensure that some prior action in the web application is causing this issue.
You can target specific cached execution plans via:
SELECT cp.plan_handle, st.[text]
FROM sys.dm_exec_cached_plans AS cp
CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS st
WHERE [text] LIKE N'%your troublesome SP or function name etc%'
And then remove only the execution plans causing issues via, for example:
DBCC FREEPROCCACHE (0x050006003FCA862F40A19A93010000000000000000000000)
I've now got a job running every 5 minutes that looks for slow running procedures or functions and automatically clears down those execution plans if it finds any:
if exists (
SELECT cpu_time, *
FROM sys.dm_exec_requests req
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS sqltext
--order by req.total_elapsed_time desc
WHERE ([text] LIKE N'%your troublesome SP or function name etc%')
and cpu_time > 8000
)
begin
SELECT cp.plan_handle, st.[text]
into #results
FROM sys.dm_exec_cached_plans AS cp
CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS st
WHERE [text] LIKE N'%your troublesome SP or function name etc%'
delete #results where text like 'SELECT cp.plan_handle%'
--select * from #results
declare #handle varbinary(max)
declare #handleconverted varchar(max)
declare #sql varchar(1000)
DECLARE db_cursor CURSOR FOR
select plan_handle from #results
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #handle
WHILE ##FETCH_STATUS = 0
BEGIN
--e.g. DBCC FREEPROCCACHE (0x050006003FCA862F40A19A93010000000000000000000000)
print #handle
set #handleconverted = '0x' + CAST('' AS XML).value('xs:hexBinary(sql:variable("#handle"))', 'VARCHAR(MAX)')
print #handleconverted
set #sql = 'DBCC FREEPROCCACHE (' + #handleconverted + ')'
print 'DELETING: ' + #sql
EXEC(#sql)
FETCH NEXT FROM db_cursor INTO #handle
END
CLOSE db_cursor
DEALLOCATE db_cursor
drop table #results
end
Simply recompiling the stored procedure (table function in my case) worked for me
like #Zane said it could be due to parameter sniffing. I experienced the same behaviour and I took a look at the execution plan of the procedure and all the statements of the sp in a row (copied all the statements form the procedure, declared the parameters as variables and asigned the same values for the variable as the parameters had). However the execution plan looked completely different. The sp execution took 3-4 seconds and the statements in a row with the exact same values was instantly returned.
After some googling I found an interesting read about that behaviour: Slow in the Application, Fast in SSMS?
When compiling the procedure, SQL Server does not know that the value of #fromdate changes, but compiles the procedure under the assumption that #fromdate has the value NULL. Since all comparisons with NULL yield UNKNOWN, the query cannot return any rows at all, if #fromdate still has this value at run-time. If SQL Server would take the input value as the final truth, it could construct a plan with only a Constant Scan that does not access the table at all (run the query SELECT * FROM Orders WHERE OrderDate > NULL to see an example of this). But SQL Server must generate a plan which returns the correct result no matter what value #fromdate has at run-time. On the other hand, there is no obligation to build a plan which is the best for all values. Thus, since the assumption is that no rows will be returned, SQL Server settles for the Index Seek.
The problem was that I had parameters which could be left null and if they were passed as null the would be initialised with a default value.
create procedure dbo.procedure
#dateTo datetime = null
begin
if (#dateTo is null)
begin
select #dateTo = GETUTCDATE()
end
select foo
from dbo.table
where createdDate < #dateTo
end
After I changed it to
create procedure dbo.procedure
#dateTo datetime = null
begin
declare #to datetime = coalesce(#dateTo, getutcdate())
select foo
from dbo.table
where createdDate < #to
end
it worked like a charm again.
--BEFORE
CREATE PROCEDURE [dbo].[SP_DEMO]
(
#ToUserId bigint=null
)
AS
BEGIN
SELECT * FROM tbl_Logins WHERE LoginId = #ToUserId
END
--AFTER CHANGING TO IT WORKING FINE
CREATE PROCEDURE [dbo].[SP_DEMO]
(
#ToUserId bigint=null
)
AS
BEGIN
DECLARE #Toid bigint=null
SET #Toid=#ToUserId
SELECT * FROM tbl_Logins WHERE LoginId = #Toid
END

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