Overview of DB2 10 and DB2 11 SQL Enhancements. Christopher J. Crone IBM

Transcription

1 Overview of DB2 10 and DB2 11 SQL Enhancements Christopher J. Crone IBM

2 2 Agenda Overview of DB2 Family SQL Functionality Review of DB2 10 SQL Enhancements Introduction to DB2 11 Enhancements Summary of recent enhancements

3 DB2 SQL DB2 10 for z/os and DB Linux, Unix & Windows z (not exhaustive, some features may be missing) Multi-row INSERT, FETCH & multi-row cursor UPDATE, dynamic scrollable cursors, GET DIAGNOSTICS, join across encoding schemes, IS NOT DISTINCT FROM, VARBINARY, FETCH CONTINUE, SELECT from MERGE, routine versions, time zone support 3 c o m m o n l u w Inner and outer joins, table expressions, subqueries, GROUP BY, complex correlation, global temporary tables, CASE, 100+ built-in functions including SQL/XML, limited fetch, insensitive scrollable cursors, UNION everywhere, MIN/MAX single index, self-referencing updates with subqueries, sort avoidance for ORDER BY, row expressions, CALL from trigger, statement isolation, range partitioning, 2M statement length, GROUP BY expression, sequences, scalar fullselect, materialized query tables, common table expressions, recursive SQL, CURRENT PACKAGE PATH, VOLATILE tables, star join, sparse index, qualified column names, multiple DISTINCT clauses, ON COMMIT DROP, transparent ROWID column, FOR READ ONLY, KEEP UPDATE LOCKS, SET CURRENT SCHEMA, client special registers, long SQL object names, SELECT FROM INSERT, UPDATE or DELETE, INSTEAD OF trigger, SQL PL in routines, file reference variables, XML, FETCH FIRST & ORDER BY in subselect/fullselect, EXCEPT, INTERSECT, MERGE, BIGINT, caseless comparisons, not logged tables, text search functions, spatial, data compression, DECFLOAT, optimistic locking, ROLE, TRUNCATE, index & XML compression, created temps, inline LOB, administrative privileges, implicit cast, datetime enhancements, currently committed, moving sum & average, index include columns, row and column access controls, time travel query, trusted contexts Updateable UNION in views, GROUPING SETS, ROLLUP, CUBE, more built-in functions, SET CURRENT ISOLATION, MDC, XQuery, XML enhancements, global variables, temp table compression, user-defined array types 3

4 DB2 SQL DB2 11 for z/os and DB Linux, Unix & Windows z c o m m o n l u w 4 (not exhaustive, some features may be missing) Multi-row INSERT, FETCH & multi-row cursor UPDATE, dynamic scrollable cursors, GET DIAGNOSTICS, join across encoding schemes, IS NOT DISTINCT FROM, VARBINARY, FETCH CONTINUE, SELECT FROM MERGE, routine versions, time zone support, transparent archive query, accelerated tables Inner and outer joins, table expressions, subqueries, GROUP BY, complex correlation, global temporary tables, CASE, 100+ built-in functions including SQL/XML, limited fetch, insensitive scrollable cursors, UNION everywhere, MIN/MAX single index, self-referencing updates with subqueries, sort avoidance for ORDER BY, row expressions, CALL from trigger, statement isolation, range partitioning, 2M statement length, GROUP BY expression, sequences, scalar fullselect, materialized query tables, common table expressions, recursive SQL, CURRENT PACKAGE PATH, VOLATILE tables, star join, sparse index, qualified column names, multiple DISTINCT clauses, ON COMMIT DROP, transparent ROWID column, FOR READ ONLY, KEEP UPDATE LOCKS, SET CURRENT SCHEMA, client special registers, long SQL object names, SELECT FROM INSERT, UPDATE or DELETE, INSTEAD OF trigger, SQL PL in routines, file reference variables, XML, FETCH FIRST & ORDER BY in subselect/fullselect, EXCEPT, INTERSECT, MERGE, BIGINT, caseless comparisons, not logged tables, text search functions, spatial, data compression, DECFLOAT, optimistic locking, ROLE, TRUNCATE, index & XML compression, created temps, inline LOB, administrative privileges, implicit cast, datetime enhancements, currently committed, moving sum & average, index include columns, row and column access controls, time travel query, trusted contexts, global variables, GROUPING SETS, ROLLUP, CUBE, DROP COLUMN, user-defined array types, XQuery Updateable UNION in views, more built-in functions, SET CURRENT ISOLATION, MDC, XML enhancements, additional user-defined types (row and cursor), MODULEs, column organized tables (BLU Acceleration), parameter defaults 4

5 Review of DB2 10 SQL Enhancements 5

6 OLAP Specification New in DB2 10 Moving Sum, Moving Average 6

7 OLAP Specification (Window Functions???) 7 RANK/DENSE_RANK ROW_NUMBER

8 Example: RANK 8 SELECT EMPNO, LASTNAME, SALARY+BONUS AS TOTAL_SALARY, RANK() OVER(ORDER BY SALARY+BONUS DESC) AS RANK_SALARY FROM DSN8A10.EMP WHERE SALARY+BONUS > ORDER BY RANK_SALARY; EMPNO LASTNAME TOTAL_SALARY RANK_SALARY _ HAAS _ HEMMINGER _ LUCCHESI _ THOMPSON _ GEYER _ KWAN _ PULASKI _ STERN _ LUTZ _ JOHN _ HENDERSON

9 Example: DENSE_RANK 9 SELECT EMPNO, LASTNAME, SALARY+BONUS AS TOTAL_SALARY, DENSE_RANK() OVER(ORDER BY SALARY+BONUS DESC) AS RANK_SALARY FROM DSN8A10.EMP WHERE SALARY+BONUS > ORDER BY RANK_SALARY; EMPNO LASTNAME TOTAL_SALARY RANK_SALARY _ HAAS _ HEMMINGER _ LUCCHESI _ THOMPSON _ GEYER _ KWAN _ PULASKI _ STERN _ LUTZ _ JOHN _ HENDERSON

10 Example: ROW_NUMBER 10 SELECT EMPNO, LASTNAME, SALARY+BONUS AS TOTAL_SALARY, ROW_NUMBER() OVER(ORDER BY SALARY+BONUS DESC) AS RANK_SALARY FROM DSN8A10.EMP WHERE SALARY+BONUS > ORDER BY RANK_SALARY; EMPNO LASTNAME TOTAL_SALARY RANK_SALARY _ HAAS _ HEMMINGER _ LUCCHESI _ THOMPSON _ GEYER _ KWAN _ PULASKI _ STERN _ LUTZ _ JOHN _ HENDERSON

11 11 DB OLAP Specification defined using a window. A window may specify three components (each is optional). Partitioning PARTITION BY CLAUSE Ordering ORDER BY clause Aggregation group ROWS/RANGE

12 12 Compute the average sales over the current month and the preceding two months for each territory and month. SELECT Territory, Month, Sales, AVG(Sales) OVER(PARTITION BY Territory ORDER BY Month ROWS 2 PRECEDING) AS Moving_Average FROM Sales_History;

13 13 Territory Month Sales Moving_Average East East East East East West West West West West

14 Compute the cumulative sum of sales in each territory, ordered by month. 14 SELECT Territory, Month, Sales, SUM(Sales) OVER(PARTITION BY Territory ORDER BY Month ASC ROWS UNBOUNDED PRECEDING) AS Cumulative_Sum FROM Sales_History; 14

15 15 Territory Month Sales Cumulative_Sum East East East East East West West West West West

16 16 Timestamp Enhancements 16

17 Timestamp Enhancements (6) WITHOUT TIME ZONE-+ >---+--TIMESTAMP >< +--(integer) WITH TIME ZONE Number of fractional digits in a timestamp extended Range supported in V10 0 to 12 digits (default is 6) Other capabilities like timestamp duration and CURRENT TIMESTAMP extended to support new precision capability SQL statements support ODBC and JDBC string representation of a timestamp as an input value only The ODBC and JDBC string representation of a timestamp has the form yyyy-mm-dd-hh:mm:ss.nnnnnn Example representation of TSwTZ: :00' :00' :00'

18 18 TIMESTAMP WITH TIMEZONE OVERVIEW New data type TIMESTAMP WITH TIME ZONE New special registers SESSION TIME ZONE CURRENT TIMESTAMP (p) WITH TIME ZONE New system parameter implicit time zone IMPLICIT_TIMEZONE TIMESTAMP WITH TIME ZONE constant TIMESTAMP string-constant A new Scalar function TIMESTAMP_TZ A new time-zone-specific-expression <timestamp expression> AT TIME ZONE <time zone expression> Existing functions takes new parameter or new data type

19 SELECT result (new data type) 19 SELECT returns external representation in stored time zone: Local timestamp (UTC + stored time zone) Time zone (stored time zone) Example: CREATE TABLE CALLCENTER (CALL_TIME TIMESTAMP WITH TIME ZONE, CALLER_ID INTEGER NOT NULL); INSERT INTO CALLCENTER VALUES(' :00, 1); INSERT INTO CALLCENTER VALUES(' :00, 2); SELECT * FROM CALLCENTER; Result: CALL_TIME CALLER_ID : :00 2

20 SPECIAL REGISTERS 20 CURRENT SESSION TIME ZONE specifies the time zone of the application process. VARCHAR(128), Format: 'tzh:tzm Default: Equivalent time zone as CURRENT TIME ZONE (internal convert) CURRENT TIMESTAMP(p) WITH TIME ZONE returns server timestamp with time zone SET SESSION TIME ZONE statement assigns a value to the special register. Example: SET SESSION TIME ZONE = -8:00'; SELECT SESSION TIME ZONE FROM SYSIBM.SYSDUMMY1; will return -08:00 SELECT CURRENT TIMESTAMP, CURRENT TIME ZONE, CURRENT TIMESTAMP WITH TIME ZONE FROM SYSIBM.SYSDUMMY1; returns CURRENT TIMESTAMP CURRENT TIME ZONE CURRENT TIMESTAMP WITH TIME ZONE :00 20

21 21 New system parameter implicit time zone A new DB2 DSNHDECP parameter IMPLICIT_TIMEZONE is provided to indicate the default time zone to associate with the TIMESTAMP WITHOUT TIME ZONE values: CURRENT: use CURRENT TIMEZONE This is default SESSION: use SESSION TIMEZONE Explicitly specify a time zone value, i.e. IMPLICIT_TIMEZONE = -00:00 Example: SET SESSION TIME ZONE = -4:00'; INSERT INTO CALLCENTER VALUES(' :00, 1); INSERT INTO CALLCENTER VALUES(' , 2); SELECT * FROM CALLCENTER WHERE CALL_TIME = ' ; Result: CALL_TIME CALLER_ID :00 2

22 Comparison (new data type) Two TIMESTAMP WITH TIME ZONE values are considered to be the same if they represent the same instant of UTC format, regardless of the time zone offsets that are stored in the data. The predicate can be sargable and indexable. Example: CREATE TABLE CALLCTR (CALL_TIME TIMESTAMP WITH TIME ZONE, CALLER_ID INTEGER NOT NULL); INSERT INTO CALLCTR VALUES(' :00, 1); INSERT INTO CALLCTR VALUES(' :00, 2); SELECT * FROM CALLCTR WHERE CALL_TIME = ' :00 ; Result: CALL_TIME CALLER_ID : :

23 23 TIMESTAMP_TZ Scalar function TIMESTAMP_TZ >>-TIMESTAMP_TZ--(--expression )--->< '-,--expression-2-' Returns a TIMESTAMP WITH TIME ZONE value from the input arguments. Example: TIMESTAMP_TZ(TIMESTAMP , -7:00 ) returns TIMESTAMP WITH TIME ZONE :00 TIMESTAMP_TZ( , -6:00, 3) returns TIMESTAMP WITH TIME ZONE :00 TIMESTAMP_TZ( ) returns TIMESTAMP WITH TIME ZONE :00 (if implicit time zone is set as -7:00)

24 24 Extract Scalar function EXTRACT TIMEZONE_HOUR or TIMEZONE_MINUTE (existing function with new options) >>--EXTRACT (--+-HOUR FROM -+-date-expression )< -MINUTE time-expression SECOND timestamp-expression- -TIMEZONE_HOUR--- '-TIMEZONE_MINUTE-' Returns time zone hour or time zone minute portion of timestamp-with-time zone expression. If the datetime argument includes a time zone, the result is determined from the UTC representation of the timestamp-with-time zone-expression value. Example: Assume that host variable PRSTSZ contains ' :30 EXTRACT(HOUR FROM :PRSTSZ) returns 4 (in UTC) EXTRACT(TIMEZONE_HOUR FROM :PRSTSZ) returns -8 EXTRACT(TIMEZONE_MINUTE FROM :PRSTSZ) return -30

25 25 Implicit Casting 25

26 26 Implicit Casting When two operands of an operation such as assignment or comparison have incompatible data types (numeric data from/to character or string data), DB2 will implicitly convert one operand to a data type that is compatible with the other. This extends the compatibility rules so that character or graphic string data types and numeric data types become compatible

27 27 Implicit Cast from Numeric Types to String Types Source Data Type SMALLINT INTEGER BIGINT NUMERIC/DECIMAL REAL FLOAT DOUBLE DECFLOAT Target Data Type VARCHAR(6) VARCHAR(11) VARCHAR(20) VARCHAR(precision+2) VARCHAR(24) VARCHAR(24) VARCHAR(24) VARCHAR(42)

28 28 Implicit Cast from String Types to Numeric Types Source Data Type CHAR VARCHAR GRAPHIC VARGRAPHIC CHAR/VARCHAR FOR BIT DATA BINARY VARBINARY BLOB CLOB DBCLOB Target Data Type DECFLOAT(34) DECFLOAT(34) DECFLOAT(34) DECFLOAT(34) N/A N/A N/A N/A N/A N/A

29 29 ROW and COLUMN ACCESS CONTROL 29

30 30 New Terminology Row Permission A row permission is a database object that expresses a row access control rule for a specific table. A row permission is a rule in the form of an SQL search condition that describes to which rows users have access. Row permissions are applied after the checking of table privileges (e.g. SELECT, INSERT) Column Mask A column mask is a database object that expresses a column access control rule for a specific column in a table. A column mask contains the rule in the form of an SQL CASE expression that describes to what masked value returned for the column value users have access. Column masks are applied after the checking of table privileges (e.g. SELECT, UPDATE)

31 31 Row Permission Row filtering Who can see what rows Applicable to SELECT, INSERT, UPDATE, DELETE, MERGE New object CREATE PERMISSION permission-name ON table-name FOR ROWS WHERE search-condition ENFORCED FOR ALL ACCESS ENABLE; Created by SECADM authority only Job card,user=secadm, Row permission definition can reference any objects except target table

32 32 Column Mask Column masking Who can see what value for an output column Applicable to the final result table New object CREATE MASK mask-name ON table-name FOR COLUMN column-name RETURN CASE-expression ENABLE; Created by SECADM authority only Job card,user=secadm, Column mask definition can reference any objects except target table

33 33 Activate Row and Column Access Control Activated by SECADM authority only Job card,user=secadm, Invalidate packages and cached statements Row permissions and column masks become effective in DML All row permissions are merged to filter out rows Multiple row permissions are connected with OR All column masks are applied to mask output columns Generate default row permission 1 = 0 if activated for row ALTER TABLE table-name ACTIVATE ROW ACCESS CONTROL ACTIVATE COLUMN ACCESS CONTROL; ALTER TABLE table-name ACTIVATE ROW ACCESS CONTROL;

34 34 Deactivate Row and Column Access Control Deactivated by SECADM authority only Job card,user=secadm, Invalidate packages and cached statements Row permissions and column masks become ineffective in DML Remove default row permission 1 = 0 if deactivated for row Open all access to the table ALTER TABLE table-name DEACTIVATE ROW ACCESS CONTROL DEACTIVATE COLUMN ACCESS CONTROL; ALTER TABLE table-name DEACTIVATE ROW ACCESS CONTROL;

35 35 Use case scenario CUSTOMER table contains information about the bank customers INTERNAL_INFO table contains information about bank employees The bank has a security policy for access to customer information Table: CUSTOMER Account Name Income Branch Alice 22,000 A Bob 71,000 B Carl 123,000 B David 172,000 C

36 36 Use Case Scenario (Cont d) ROW PERMISSION FOR TELLERS CREATE PERMISSION TELLER_ROW_ACCESS ON CUSTOMER FOR ROWS WHERE VERIFY_ROLE_FOR_USER (USER, TELLER ) = 1 AND BRANCH = (SELECT HOME_BRANCH FROM INTERNAL_INFO WHERE EMP_ID = USER) ENFORCED FOR ALL ACCESS ENABLE ROW PERMISSION FOR CSR and TELEMARKETER CREATE PERMISSION CSR_ROW_ACCESS ON CUSTOMER FOR ROWS WHERE VERIFY_ROLE_FOR_USER (USER, CSR ) = 1 OR VERIFY_ROLE_FOR_USER (USER, TELEMARKETER ) = 1 ENFORCED FOR ALL ACCESS ENABLE

37 37 Use Case Scenario (Cont d) COLUMN MASK FOR ACCOUNT NUMBER CREATE MASK ACCOUNT_COL_MASK ON CUSTOMER FOR COLUMN ACCOUNT RETURN CASE WHEN (VERIFY_ROLE_FOR_USER (USER, TELEMARKETER ) = 1) THEN 'xxxx-xxxx-xxxx- SUBSTR(ACCOUNT,13,4) ELSE ACCOUNT END ENABLE ACTIVATE ROW AND COLUMN LEVEL ACCESS CONTROL ALTER TABLE CUSTOMER ACTIVATE ROW LEVEL ACCESS CONTROL ACTIVATE COLUMN LEVEL ACCESS CONTROL

38 38 Use Case Scenario Cont d Teller Amy issues the following query SELECT ACCOUNT, NAME, BRANCH FROM CUSTOMER Account Name Income Branch Bob 71,000 B Carl 123,000 B Telemarketer Pat issues the following same query Account Name Income Branch XXXX-XXXX-XXXX-4444 Alice 22,000 A XXXX-XXXX-XXXX-5555 Bob 71,000 B XXXX-XXXX-XXXX-6666 Carl 123,000 B XXXX-XXXX-XXXX-7777 David 172,000 C

39 39 Miscellaneous SQL Enhancements 39

40 40 SQL Syntax Compatibility items Synonyms UNIQUE (synonym for DISTINCT) MINUS (synonym for EXCEPT) seqname.nextval synonym for NEXT VAL FOR seqname seqname.currval synonym for PREVIOUS VALUE FOR seqname FROM clause on DELETE is optional CROSS JOIN Cartesian Product - inner join with WHERE 1 = 1 predicate Cursor with Return to client

41 41 Additional Built In Function Capability TO_CHAR (*extended function*) - see VARCHAR_FORMAT VARCHAR_FORMAT (*extended function*) Additional Format Models Format string is optional Additional datatype support BITxxx 5 bit manipulation functions BITAND, BITANDNOT, BITOR, BITXOR, BITNOT DECODE Transform into CASE expression TO_NUMBER Synonym for DECFLOAT_FORMAT and additional function NVL - > Synonym for COALESCE

42 Introduction to DB2 11 Enhancements 42

43 SQL PL Array Data Type 43

44 Review of SQL Procedures What is an SQL Stored Procedure? A stored procedure that contains only SQL statements May use SQL control statements to write the logic part of the program (e.g. WHILE, IF, GOTO, REPEAT, etc.) SQL Procedural Language or SQL PL 44 Two types of SQL Stored Procedures External SQL Procedures (from V5 on) - Generated C program which runs in a WLM environment Native SQL Procedures (from DB2 9 on) - The SQL procedure logic runs in the DBM1 address space

45 Native SQL Procedure Processing 45 z/os Appl pgm CALL SP1 DB2 DBM1 DDF Appl pgm SP1 SQL PL native logic SQL SQL CALL SP1 EDM pool DB2 directory SP1 SQL PL native logic SQL SQL *native SQL procedures do not run IN the WLM address space but are still running UNDER the WLM

46 Array Data Type Overview DB2 for z/os introduces support for Arrays inside SQL Routines (UDFs or Procedures). Prior to DB2 11, users might have utilized the following mechanisms to pass data to/from Routines: DECLARED GLOBAL TEMPORARY TABLE, Concatenated Strings, Long lists of parameters, or The Array Data Type consists of an ordered set of elements having the same data type (length, precision, scale, CCSID as appropriate) Two Types of Arrays are Supported: Ordinary Arrays Have a maximum cardinality (2 Billion) The data type of the index value is INTEGER Associative Arrays Do not have a defined upper bound on the number of elements The data type of the index values can be an INTEGER or character string (not a LOB) 46

47 Creating an Array Type 47 CREATE Ordinary and Associative arrays via CREATE TYPE statement All types except XML If data-type2 is specified, then array is an Associative Array -- ordinary array with integer value & integer index CREATE TYPE OrdIntArray AS INTEGER ARRAY[100]; -- associative array with integer value & integer index CREATE TYPE AssocIntArray AS INTEGER ARRAY[INT]; -- associative array with integer value & varchar index CREATE TYPE AssocIntArrayVarIdx AS INTEGER ARRAY[VARCHAR(13)];

48 Creating a Native SQL Routine with Array Arguments 48 CREATE FUNCTION (SQL scalar) Array elements may only be sent in as an argument to a function (whole) Arrays may be passed in as an argument or a result of a function CREATE PROCEDURE (SQL native) Array elements may only be sent in as an IN parm to a procedure (whole) Arrays may be passed in as IN, OUT, or INOUT parms for a procedure -- create a UDF that accepts and returns an ordinary array CREATE FUNCTION UDF1 (P1 OrdIntArray, P2 INTEGER) RETURNS OrdIntArray BEGIN END; -- ordinary array with integer value & integer index CREATE TYPE OrdIntArray AS INTEGER ARRAY[100]; -- associative array with integer value & varchar index CREATE TYPE AssocIntArrayVarIdx AS INTEGER ARRAY[VARCHAR(13)]; -- create a procedure that accepts and returns an associative array CREATE PROCEDURE PROC2 (IN InP1 INTEGER, IN InP2 AssocIntArrayVarIdx, INOUT InOutP1 AssocIntArrayVarIdx, OUT OutP1 AssocIntArrayVarIdx) BEGIN END;

49 Declaring Array Variables DECLARE Ordinary and Associative arrays via SQL-variable-declaration create a UDF that accepts and returns an ordinary array CREATE FUNCTION UDF1 (P1 OrdIntArray, P2 INTEGER) RETURNS OrdIntArray BEGIN -- declare two ordinary array with same array type DECLARE myordintarray OrdIntArray; DECLARE my2ndordintarray OrdIntArray; END; -- ordinary array with integer value & integer index CREATE TYPE OrdIntArray AS INTEGER ARRAY[100]; -- associative array with integer value & varchar index CREATE TYPE AssocIntArrayVarIdx AS INTEGER ARRAY[VARCHAR(13)]; -- create a procedure that accepts and returns an associative array CREATE PROCEDURE PROC2 (IN InP1 INTEGER, IN InP2 AssocIntArrayVarIdx, INOUT InOutP1 AssocIntArrayVarIdx, OUT OutP1 AssocIntArrayVarIdx) BEGIN -- declare two associative arrays with the same array type DECLARE myassocintarray AssocIntArrayVarIdx; DECLARE myassocintarray AssocIntArrayVarIdx; END;

50 Assigning values to Arrays Construct arrays with array-constructor and assign values with SET assignment-statement create a UDF that accepts and returns an ordinary array CREATE FUNCTION UDF1 (P1 OrdIntArray, P2 INTEGER) RETURNS OrdIntArray BEGIN -- declare two ordinary array with same array type DECLARE myordintarray OrdIntArray; DECLARE my2ndordintarray OrdIntArray; -- set an ordinary array with 3 values using an array-constructor SET myordintarray = ARRAY[10,20,30]; myordintarray Index Value set a 2nd ordinary array s array element, using array-element-specification SET my2ndordintarray[1] = myordintarray[3]; END; -- ordinary array with integer value & integer index CREATE TYPE OrdIntArray AS INTEGER ARRAY[100]; -- associative array with integer value & varchar index CREATE TYPE AssocIntArrayVarIdx AS INTEGER ARRAY[VARCHAR(13)]; my2ndordintarray Index Value 1 30

51 Build an Array from Table Data ARRAY_AGG Aggregate Function The ARRAY_AGG function returns an array where each value of the input set is assigned to an element of the array. CREATE TYPE OrdVchArray AS VARCHAR(12) ARRAY[100]; 51 DECLARE myordvcharray OrdVchArray; SET myordvcharray = (SELECT ARRAY_AGG(PHONE) FROM EMPLOYEE WHERE ID IS NOT NULL ORDER BY ID, PHONE); EMPLOYEE myordvcharray ID PHONE Index Value

52 Treating an Array Like a Table 52 Treat an array like a table i.e. fetch data from the array (using UNNEST collection-derived-table) just like you would from a table from-clause collection-derived-table A collection-derived-table can be used to convert the elements of one or more arrays into column values in separate rows of an intermediate result table Associative Array Example SELECT T.State, T.Population FROM UNNEST(myAssocIntArray) AS T(State,Population); myassocintarray Index Value California Oregon State Population California Oregon

53 Deleting Elements From An Array ARRAY_DELETE Scalar Function The ARRAY_DELETE function deletes elements from an array. The result of the function has the same data type as array-expression. 53 myassocintarray -- create a procedure that accepts and returns an associative array CREATE PROCEDURE PROC2 (IN InP1 INTEGER, IN InP2 AssocIntArrayVarIdx, INOUT InOutP1 AssocIntArrayVarIdx, OUT OutP1 AssocIntArrayVarIdx) BEGIN -- declare two associative arrays with the same array type DECLARE myassocintarray AssocIntArrayVarIdx; -- set an associative array with 5 values SET myassocintarray['california'] = ; SET myassocintarray['oregon'] = ; SET myassocintarray[new York'] = ; SET myassocintarray[ New Hampshire'] = 18000; -- remove the state of Oregon from the array SET myassocintarray = ARRAY_DELETE(myAssocIntArray, Oregon ); -- remove all states that begin with New from the array SET myassocintarray = ARRAY_DELETE(myAssocIntArray, New Hampshire, New York ); END; Index Value California New Hampshire New York Oregon myassocintarray Index Value California New Hampshire New York myassocintarray Index Value California

54 Finding an Array Element Index Name ARRAY_FIRST ARRAY_LAST ARRAY_NEXT ARRAY_PRIOR Description returns the minimum array index value of the array returns the maximum array index value of the array returns the next larger array index value for an array relative to the specified array index argument returns the next smaller array index value for an array relative to the specified array index argument -- create a procedure that accepts and returns an associative array CREATE PROCEDURE PROC2 (IN InP1 INTEGER, IN InP2 AssocIntArrayVarIdx, INOUT InOutP1 AssocIntArrayVarIdx, OUT OutP1 AssocIntArrayVarIdx) BEGIN -- declare local varchar variable DECLARE myvarchar, my2ndvarchar VARCHAR(20); -- declare two associative arrays with the same array type DECLARE myassocintarray AssocIntArrayVarIdx; -- set an associative array with 2 values SET myassocintarray['california'] = ; SET myassocintarray['oregon'] = ; sets a local variable to the index that follows California SET myvarchar = ARRAY_NEXT(myAssocIntArray, California ); END; myvarchar = Oregon

55 Autonomous Transactions 55

56 Autonomous Transactions An Autonomous Transactions is: A native SQL procedure that runs in its own unit of work May perform SQL, COMMITs, and ROLLBACK it s own SQL No uncommitted changes from it s caller are seen Locks are not shared between the caller and the autonomous procedure Upon completion of the autonomous procedure, a COMMIT is driven for the autonomous procedure when SQLCODE >=0 The caller s work is untouched Useful for event or audit logs 56 z/os Appl pgm INSERT INTO T1 CALL AutoTran_STP; ROLLBACK; T1 modifications unseen T2 committed but not T1 DB2 DBM1 AutoTran_STP: AutoTran_STP: BEGIN BEGIN UPDATE T2 UPDATE T2 END; END;

57 Creating & displaying autonomous transactions Specify AUTONOMOUS keyword on CREATE PROCEDURE or ALTER PROCEDURE statement s option-list 57 Display autonomous transaction state with -DISPLAY THREAD(*) command DB1G DISPLAY THREAD(*) STC00090 DSNV401I DB1G DISPLAY THREAD REPORT FOLLOWS STC00090 DSNV402I DB1G ACTIVE THREADS - NAME ST A REQ ID AUTHID PLAN ASID TOKEN BATCH SP * 1 APPLX USER001 PL01AP AT * 641 APPLX USER001 PL01AP01 002A 13

58 Global Variables 58

59 Global Variables Overview Benefits Allows users to share information across SQL statements Allows capability to set once, use everywhere Provides additional security via DB2 GRANT and REVOKE Characteristics Similar to special registers Their definitions are global and shared across different connections Their contents are only shared within the same connection Each connection maintains its own instantiation Their contents are NOT affected by COMMIT nor ROLLBACK Use only the UNICODE encoding scheme 59

60 Writing and Reading Global Variables WRITE to via: SET, SELECT INTO, VALUES INTO, OUT or inout parms READ from via: Anywhere an expression can be specified Exceptions check constraints, MQTs, views with WITH CHECK OPTION, keys (index on expressions, XML indexes, spatial indexes), arrays Values are locked in as soon as the following: View definition SQL scalar UDF or table UDF body Trigger action Row permission definition Column mask definition Auto-binding a package 60

61 Using and Referencing a Global Variable Create a global variable via new CREATE VARIABLE statement 61 Setting and referencing a global variable -- create a global variable CREATE VARIABLE Charge_Rate DECIMAL(4,2) DEFAULT 0.00; -- create a procedure that determines charge rate CREATE PROCEDURE Loan_Charge_Rate (IN ID CHAR(5)) BEGIN.. SELECT SCORE INTO Cust_Score FROM CUSTOMER WHERE ACCOUNT = ID; IF Cust_Score = Good THEN SET Charge_Rate = 1.0; ELSE SET Charge_Rate = 3.0; END; -- calling application myapp: PROCEDURE(Buyer, Amount); CALL Loan_Charge_Rate(Buyer); UPDATE CUSTOMER SET BALANCE = BALANCE + (Amount * Charge_Rate); END myapp;

62 Grouping Sets 62

63 Enhanced subselect group-by-clause 63 subselect group-by-clause

64 Syntax: grouping-sets and super-groups grouping-sets 64 super-groups

65 New Aggregations Grouping Sets Grouping sets allow multiple groups to be specified Querying and reporting are made easier and faster by producing a single result from essentially performing a UNION ALL of two or more groups of rows group-by-clause has been enhanced: grouping-sets Allows multiple grouping clauses to be specified in a single statement Allows the groups to be computed with a single pass over the data Can be used to determine subtotals and grand totals super-groups i.e. for a given group, calculate it s subtotal as well as the grand total for all groups Pre-defined grouping-sets ROLLUP CUBE 65

66 Predefined Grouping Sets - ROLLUP 66 ROLLUP Creates subtotals that roll up from the most detailed level to a grand total N elements translate to N+1 grouping sets: GROUP BY ROLLUP (C1,C2,C3) equivalent GROUP BY GROUPING SETS ((C1,C2,C3), (C1,C2), (C1), ()); The order specified is significant to the result: GROUP BY ROLLUP (C1,C2) equivalent GROUP BY GROUPING SETS ((C1,C2), (C1), ()); versus GROUP BY ROLLUP (C2,C1) equivalent GROUP BY GROUPING SETS ((C2,C1), (C2), ());

67 67 Predefined Grouping Sets - CUBE CUBE Creates subtotals for all permutations N elements translate to 2 n grouping sets: GROUP BY CUBE (C1,C2,C3) 3 elements equivalent 8 groups GROUP BY GROUPING SETS ( (C1,C2,C3), (C1,C2), (C1,C3), (C2,C3), (C1), (C2), (C3), ()); Unlike ROLLUP, the order specified is NOT significant to the result i.e. use ORDER BY to guarantee the order grand-total the overall aggregation of previous subtotals Both CUBE and ROLLUP return this row as the last row grand-total

68 68 GROUPING Aggregate Function Used to indicate whether or not the row was returned as a result of a grouping set i.e. the GROUPING aggregate function tells you the result of the grouping set was NULL versus the source row of the grouping set was NULL 1 0 the NULL value was generated by a super-group the NULL value is from the source row

69 GROUP BY GROUPING SETS - Example Example: Create a result set from the SALES table based on person and date. SELECT WEEK(SALES_DATE) as WEEK, DAYOFWEEK(SALES_DATE) AS DAY, SALES_PERSON, SUM(SALES) AS SOLD FROM SALES WHERE SALES_DATE > ' GROUP BY GROUPING SETS (WEEK(SALES_DATE), DAYOFWEEK(SALES_DATE), SALES_PERSON) 69 69

70 GROUP BY ROLLUP 70 An extension to the GROUP BY clause Produces a result set that contains sub-total rows. The sequence of the columns is significant. GROUP BY ROLLUP (a, b, c) is equal to GROUP BY (a, b, c) + GROUP BY (a, b) + GROUP BY (a) + grand-total Example SELECT WEEK(SALES_DATE) AS WEEK, DAYOFWEEK(SALES_DATE) AS DAY, SALES_PERSON, SUM(SALES) AS SOLD FROM SALES WHERE SALES_DATE > ' ' GROUP BY ROLLUP (WEEK(SALES_DATE), DAYOFWEEK(SALES_DATE), SALES_PERSON) ORDER BY WEEK(SALES_DATE), DAYOFWEEK(SALES_DATE), SALES_PERSON

71 71 GROUP BY ROLLUP results 71

72 GROUP BY CUBE An extension to the GROUP BY clause 72 Produces a result set that contains ROLLUP aggregation plus cross-tabulation rows. The sequence of the columns is not significant. GROUP BY CUBE (a, b, c) is equal to GROUP BY (a, b, c) + GROUP BY (a, b) + GROUP BY (a,c) + GROUP BY (b,c) + GROUP BY (a) + GROUP BY (b) + GROUP BY (c) + grand-total Example SELECT WEEK(SALES_DATE) AS WEEK, DAYOFWEEK(SALES_DATE) AS DAY, SALES_PERSON, SUM(SALES) AS SOLD FROM SALES WHERE SALES_DATE > ' ' GROUP BY CUBE (WEEK(SALES_DATE), DAYOFWEEK(SALES_DATE), SALES_PERSON) ORDER BY WEEK(SALES_DATE), DAYOFWEEK(SALES_DATE), SALES_PERSON

73 73 GROUP BY CUBE results 73

74 GROUP BY CUBE results contd

75 Summary 75

76 76 Summary DB2 10 and DB2 11 build on SQL function provided in previous releases with the following focus areas Native SQL Routines DB2 10 added Native SQL UDFs DB2 11 added the ARRAY datatype for use in SQL Routines DB2 11 added Autonomous SQL Procedures Analytic processing DB2 9 and DB2 10 Added OLAP Specification Support DB2 11 Added Cube, Rollup, and Grouping Sets Security DB2 10 added, and DB2 11 enhanced, Column Masking SQL Family and Vendor compatibility extensions Extensions needed to run popular applications requested by customers and vendors

77 Resources Requirements DB2 for z/os Information Center 2r2/index.jsp DB2 11 for z/os Technical Overview Redbook 77

78 78

79 79 Thank You Overview of DB2 10 and DB2 11 SQL Enhancements Christopher J. Crone IBM Session Code: F2 Monday November 10 th 12:00 PM Platform: DB2 for z/os