Advanced SQL Topics. Michael Fields Central Library Consortium

Transcription

1 Advanced SQL Topics Michael Fields Central Library Consortium

2 Overview

3 Useful tools SQL Complete -- SSMS add-in Better intellisense / searching Better command execution Clipboard manager Easily hold on to all sorts of random bits of data Ditto is what I personally use Winmerge Visually compare two files to make sure Polaris installed all your custom patching...

4 Views Virtual table defined by a query Can hide complex SELECT statements while being referenced in the same way as a table Can truly make your life easier Can be used to circumvent some of the limitations of the find tool provided you don t need a parameterized solution

5 Creating Views Use Polaris; CREATE VIEW CLC_Custom_PUG2014_Patrons AS SELECT * FROM Polaris.Polaris.Patrons where PatronID like '%2014%'

6 clc_custom_viewtransactiondetails CREATE view [dbo].[clc_custom_viewtransactiondetails] as select td.transactionid, th.transactiondate, tt.transactiontypedescription, td. transactionsubtypeid, tst.transactionsubtypedescription, td.numvalue from PolarisTransactions.polaris.TransactionDetails td join PolarisTransactions.polaris.TransactionSubTypes tst on td.transactionsubtypeid = tst.transactionsubtypeid join PolarisTransactions.polaris.TransactionHeaders th on td.transactionid = th.transactionid join PolarisTransactions.polaris.TransactionTypes tt on GO tt.transactiontypeid = th.transactiontypeid

7 Example command and output of the view

8 Stored Procedures Saved batch of SQL commands Can accept parameters Allows you to modify report or SQL job statements without having to use their crummy editors

9 Creating stored procedures use Polaris; go create procedure varchar(max) as begin select itemrecordid from polaris.polaris.circitemrecords where itemrecordid end

10 Calling stored procedures exec Polaris.dbo.CLC_Custom_PUG2014_Items '%2014%'

11 Sample usage in SQL job

12 Functions Cannot alter the database, only performs calculations on its input parameter(s) Two types Scalar Used inline and returns one value Table valued Used like a table and is SELECTed from

13 Scalar functions Returns one, non-optional value Predefined datatype Called inline Can be used in WHERE, HAVING, and GROUP BY

14 Creating a scalar function

15 use Polaris go CREATE FUNCTION CLC_Custom_PUG2014_Append varchar(max) ) RETURNS varchar(max) AS BEGIN + 'PUG2014' END

16 Using scalar function select Polaris.dbo.clc_custom_pug2014_append('hello ')

17 Table valued function Returns a resultset Can be joined to a SELECT query Can encapsulate statements the Polaris find tool doesn t like

18 Creating table valued function

19 use Polaris go CREATE FUNCTION CLC_Custom_PUG2014_SELECT varchar(max) ) TABLE ( mystring varchar(max) ) AS BEGIN END GO insert + 'PUG2014' RETURN

20 Using table valued function select * from Polaris.dbo.CLC_Custom_PUG2014_SELECT('hello ')

21 Sample usage table function inside SQL search

22 Output of TVF SQL search

23 Cross apply Used to join a table valued function to a SELECT statement Applies the function to each row of output and joins in the result

24 Sample cross apply with table value function

25 Transactions Saves you from yourself Connected to wrong DB Forget WHERE clause Allows you to handle errors Lets you check your work before it s real Make sure to always COMMIT or ROLLBACK all transactions; don t leave them open for extended periods of time

26 Using transactions BEGIN TRAN do stuff --ROLLBACK --COMMIT

27 Error handling with transactions set xact_abort on Automatically rolls back if SQL errors are encountered Easier; only one line to add, added before transaction Possibly faster, although probably negligible try/catch More flexible but also more complex Allows you to do things other than just roll back

28 Example try/catch BEGIN TRY BEGIN TRANSACTION insert into Polaris.Polaris.ItemAvailabilityDisplay values ( 1,1,1,1,1 ) COMMIT END TRY BEGIN CATCH ROLLBACK select ERROR_MESSAGE() END CATCH

29 Error from our transaction before

30 Example with rollback ItemAvailabilityDisplay showing no entry for Organization 1 and BranchLocation 1

31 BEGIN TRY BEGIN TRANSACTION insert into Polaris.Polaris.ItemAvailabilityDisplay values ( 1,1,1,1,1 ) select 1 / 0 COMMIT END TRY BEGIN CATCH ROLLBACK select ERROR_MESSAGE() END CATCH Inserting a row inside our try/catch and transaction followed by a guaranteed error

32 Error from our statement, no data was inserted into the table

33 Loops Bad, avoid when possible Always slower than set based statements Necessary in some odd situations

34 Using loops INT = 1 <= 10 BEGIN do stuff here + 1 END

35 ...but don t do that, unless absolutely necessary

36 Loop alternatives GROUP BY Useful for adding entries at the bottom for each branch CROSS APPLY Apply a table valued function to each row in a resultset CROSS JOIN RANK() Copy settings to new branches (Fine Codes, Loan Periods, etc) Bulk insert entries (DatesClosed, Collections, Floating)

37 RANK Gives you the rank of each row in a resultset for the given partitioning and ordering Usage format is as follows RANK( ) OVER ([ partition_by_clause ] order_by_clause)

38 RANK sample usage statement

39 Output of our sequence-fixing RANK function

40 Using GROUP BY to eliminate loops select [Responder], MAX(shrs.Sequence) + 1 [sequence], 5 [maxdays], 2 [primarysecondary] from Polaris.polaris.SysHoldRoutingSequences shrs group by shrs.requesterbranchid

41 Portion of the results from the sample GROUP BY command

42 Temporary tables True temporary tables (#name) Require more effort to create and use Can be explicitly indexed More appropriate for large sets of data Table variables Quick and easy to use Can only be implicitly indexed by the use of UNIQUE and PRIMARY KEY Only for smaller sets of data

43 Temporary table example create table #Pug2014 ( id int, col1 varchar(max), col2 varchar(max) ) insert into #Pug2014 select 1, 'row1', 'row1' union all select 2, 'row2', 'row2' union all select 3, 'row3', 'row3' select * from #Pug2014 drop table #Pug2014

44 Temporary table SELECT result

45 Table variable example table ( id int, col1 varchar (max), col2 varchar(max) ) insert select 1, 'row1', 'row1' union all select 2, 'row2', 'row2' union all select 3, 'row3', 'row3' select *

46 Temporary table SELECT result

47 Cross joins Few use scenarios However, can save you gobs of time when inserting into certain Polaris tables Joins every row in Table A to every row in Table B Can make ludicrous amounts of data if used on two tables of even modest size

48 Cross join goodness Adding list of closed dates to all branches table ( closeddate date ) insert values ('1/1/2001'), ('2/2/2002'), ('3/3/3003') insert into Polaris.Polaris.DatesClosed select o.organizationid, d.closeddate from Polaris.Polaris. Organizations o cross d where o.organizationcodeid = 3 order by o.organizationid

49 Portion of the result of our sample cross join

50 User defined table types Allows you to define custom table types Only real way to pass a true list of values to a stored procedure Similar to a Class in Object Oriented Programming Used almost exclusively as parameter type for stored procedures or functions

51 Creating User Defined Table Type USE [Polaris] GO CREATE TYPE [dbo].[clc_custom_org_list] AS TABLE( [OrganizationID] [int] ) GO

52 Using UDTT in stored procedure use Polaris go create procedure as dbo.clc_custom_org_list READONLY as begin select o.organizationid [id from param], o2.name [name from db] o join Polaris.Polaris.Organizations o2 on o.organizationid = o2.organizationid end

53 Example usage as clc_custom_org_list insert values (1), (3), (7) exec

54 Output from example command

55 Dynamic SQL Two ways to do it EXEC() Greater potential for SQL injection Not as optimizable by SQL Server sp_executesql Can be fully parameterized Strongly typed parameters, much safer Input statement easier to read

56 Difference between the two methods

57

58 Questions? Mike Fields