de haan - writing portable sql

©2004, Natural Join B.V. Writing Portable SQL - 1

HotsosSymposiumDallas, March 2005

ANSI/ISO SQL:Writing Portable SQL

Lex de Haan([email protected])

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Who Am I

Lex de [email protected] Maths, TU DelftOracle employee 1990-2004

– Teacher, delivery manager,product manager seminars,curriculum developer/manager,ST development

ISO SQL StandardizationMarch 2004: Natural Join B.V.http://www.naturaljoin.nl


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Topics

IntroductionANSI/ISO data types and literalsData definition (DDL)Query and table expressionsPredicates and search conditionsExpressions and functionsAnalytical functionsRecommendationsQ&A

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Advantages of ANSI/ISO SQL

Portability?Readability?Maintainability?

If you mastered the SQL language some years ago(as most of use did, right?) you might be surprised ...

– to see how the SQL language developed– to learn about some great new SQL features

implemented in recent Oracle releases


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Introduction: Standards Background

ISO: Membership by National Body– ISO/IEC/JTC1/SC32/WG3: Database languages

ANSI: Membership by organization or individual

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Introduction: Standards History

SQL-86, SQL-87, SQL-89 (referential integrity added)SQL-92

– One standard with multiple conformance levels:Entry, Transitional, Intermediate, Full

SQL:1999– Introduced multiple parts and named features:

the main part is "Core SQL"– Some parts were backported to SQL-92

SQL:2003"bug fixing" release (minor enhancements)SQL:2007 ???


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SQL:1999 and SQL:2003 Parts

1. Framework2. Foundation3. Call Level Interface (CLI)4. Persistent Stored Modules (PSM)5. Host Language Bindings (gone in SQL:2003)9. Management of External Data (MED)

10. Object Language Bindings (OLB)11. Information and Definition Schemata13. Java Routines and Types (JRT)14. XML Related Specifications (XML)

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Oracle and the ANSI/ISO Standard

Unsupported SQL/XML:2003 featuresB-10

Equivalent functionality for SQL/XML:2003 featuresB-9

Fully supported features of SQL/XML:2003B-8

Sizing for database constructsB-11

Equivalent functionality for optional features of SQL/Foundation:2003B-7

Partially supported optional features of SQL/Foundation:2003B-6

Fully supported optional features of SQL/Foundation:2003B-5

Unsupported Core SQL:2003 featuresB-4

Equivalent functionality for Core SQL:2003 featuresB-3

Partially supported Core SQL:2003 featuresB-2

Fully supported Core SQL:2003 featuresB-1

SQL Reference, Appendix B: Oracle and Standard SQL


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Data Types and Literals

Character data

Binary data

CHARACTER [VARYING][(<len>)] [CHARACTER SET <cs-name>]CLOBShorthands: CHAR(x), NCHAR(x), VARCHAR(x)

BLOBBIT [VARYING][(<len>)]Literals: B or X prefixOracle equivalent: RAW

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Exact numeric data

Approximate numeric data

NUMERIC[(p[,s])]DECIMAL[(p[,s])]INTEGER, SMALLINT, BIGINTShorthands: INT, DEC(p,s)

FLOAT[(p)]REALDOUBLE PRECISION (These three types map to NUMBER in Oracle)Oracle equivalents: BINARY_FLOAT, BINARY_DOUBLELiterals: Using E between mantissa and exponentOracle: Postfix numbers with F or D


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Datetime and intervals

Datetime and interval fields

Datetime and interval literals

DATETIME[(p)][WITH TIME ZONE] (Oracle: set event 10407)TIMESTAMP[(p)][WITH TIME ZONE]INTERVAL {<single-fld>|<start-fld> TO <end-fld>}

YEAR MONTH DAY HOUR MINUTE SECOND TIMEZONE_{HOUR|MINUTE}

DATE 'yyyy-mm-dd'TIME 'hh:mi:ss [tz-interval]'TIMESTAMP 'yyyy-mm-dd hh:mi:ss [tz-interval]'INTERVAL [+|-]'value' <qualifier>

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Miscellaneous other data types

– I think it is really a pity Oracle doesn't supportthe BOOLEAN data type...

BOOLEANROWARRAY, MULTISETUser-defined types, REF types


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Data Definition Language

Examples of some nice/powerful DDL featuresmissing in Oracle:

– Local temporary tables– Recursive view definitions– Views with cascading CHECK option

CREATE [{GLOBAL|LOCAL} TEMPORARY] TABLE ...[ON COMMIT {PRESERVE|DELETE} ROWS]

CREATE [RECURSIVE] VIEW ... AS <query>[WITH [LOCAL|CASCADED] CHECK OPTION]

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Query and Table Expressions

<q1> UNION [ALL][CORRESPONDING[BY(<col-list>)]] <q2><q1> EXCEPT [ALL][CORRESPONDING[BY(<col-list>)]] <q2><q1> INTERSECT[ALL][CORRESPONDING[BY(<col-list>)]] <q2>

<t1> CROSS JOIN <t2><t1> [NATURAL] [<join-type>] JOIN <t2> [{ON|USING} ...]<join-type>:== INNER (default)

, {LEFT|RIGHT|FULL} [OUTER], UNION

WITH [RECURSIVE] ... AS (<query>) ...


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Predicates and Search Conditions

... IS [NOT] {TRUE|FALSE|UNKNOWN}[NOT] BETWEEN ... AND ...[NOT] LIKE ... [ESCAPE ...]SIMILAR (regular expressions)IS [NOT] NULL[NOT] IN {<subquery>|<in-list>}<op> {ALL|{SOME|ANY}} (<subquery>)(a,b) OVERLAPS (c,d)MATCH [UNIQUE] [SIMPLE|PARTIAL|FULL] (<subquery>)EXISTS (<subquery>)UNIQUE (<subquery>)IS [NOT] NORMALIZED<r1> IS DISTINCT FROM <r2><r> [NOT] MEMBER [OF] <ms><ms1> [NOT] SUBMULTISET [OF] <ms2><c> IS [NOT] A SET

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Expressions and Functions

Scalar functions

USER, CURRENT_{TIMESTAMP[(p)]|DATE|TIME[(p)]}EXTRACT(<component> FROM <value>)SUBSTRING(... FROM <start-pos> [FOR <len>]){CHARACTER|OCTET|BIT}_LENGTH(...)POSITION(... IN ...)TRIM([[LEADING|TRAILING|BOTH]... FROM] <source>)UPPER, LOWERTRANSLATE(... USING...)CONVERT(... USING...)CAST({<value>|NULL} AS...)


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Expressions and Functions

Conditional value expressions

CASE abbreviations

CASE <expr> WHEN <v1> THEN <r1>... [ELSE <rn>] ENDCASE WHEN <c1> THEN <r1>... [ELSE <rn>] END

NULLIF(v1,v2) <=> CASE WHEN v1=v2THEN NULLELSE v1

END COALESCE(v1,v2,...) <=> CASE WHEN v1 IS NOT NULL

THEN v1ELSE COALESCE(v2,...)

END

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Window Functions

Window function subtypes:– Rank functions (RANK, DENSE_RANK)– Distribution functions (PERCENT_RANK, CUME_DIST)– Row number function (ROW_NUMBER)– Window aggregate functions (COUNT, SUM, AVG, ...)

table

window

current row

<window-function> OVER( [ PARTITION BY (...) ]

[ ORDER BY (...) ][{RANGE|ROWS}{BETWEEN ... AND ...| ... PRECEDING } ]

)


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SQL Standards Compliance Checker

FIPS does not certify SQL implementations anymore;today, there is no formal way to test/certify SQL.Check out the Mimer website in Sweden:

– Go to www.mimer.com– Click "Mimer SQL Developer"– Navigate to "SQL Validator"– Enter your SQL statements in the box– Click the "Test SQL" button

SQL:2003 Validator

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Some SQL Recommendations

TO_DATE('…','…'){DATE|INTERVAL|TIMESTAMP} '…'

LTRIM, RTRIMTRIM

TO_{CHAR|DATE|NUMBER}EXTRACT, CAST

NVLCOALESCE

DECODE, NVL2CASE, NULLIF

(+) syntax{LEFT|FULL|RIGHT} OUTER JOIN

Comma in FROM clauseJOIN … {USING|ON} …

Instead of:In Oracle SQL, use:


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That's All...

de haan - writing portable sql

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