## Appendix D. SQL Conformance

This section attempts to outline to what extent PostgreSQL conforms to the current SQL standard. The following information is not a full statement of conformance, but it presents the main topics in as much detail as is both reasonable and useful for users.

The formal name of the SQL standard is ISO/IEC 9075 “Database Language SQL”. A revised version of the standard is released from time to time; the most recent one appearing in late 2003. That version is referred to as ISO/IEC 9075:2003, or simply as SQL:2003. The versions prior to that were SQL:1999 and SQL-92. Each version replaces the previous one, so claims of conformance to earlier versions have no official merit. PostgreSQL development aims for conformance with the latest official version of the standard where such conformance does not contradict traditional features or common sense. The PostgreSQL project was not represented in the ISO/IEC 9075 Working Group during the preparation of SQL:2003. Even so, many of the features required by SQL:2003 are already supported, though sometimes with slightly differing syntax or function. Further moves towards conformance may be expected in later releases.

SQL-92 defined three feature sets for conformance: Entry, Intermediate, and Full. Most database management systems claiming SQL standard conformance were conforming at only the Entry level, since the entire set of features in the Intermediate and Full levels was either too voluminous or in conflict with legacy behaviors.

Starting with SQL:1999, the SQL standard defines a large set of individual features rather than the ineffectively broad three levels found in SQL-92. A large subset of these features represents the “Core” features, which every conforming SQL implementation must supply. The rest of the features are purely optional. Some optional features are grouped together to form “packages”, which SQL implementations can claim conformance to, thus claiming conformance to particular groups of features.

The SQL:2003 standard is also split into a number of parts. Each is known by a shorthand name. Note that these parts are not consecutively numbered.

- ISO/IEC 9075-1 Framework (SQL/Framework)

- ISO/IEC 9075-2 Foundation (SQL/Foundation)

- ISO/IEC 9075-3 Call Level Interface (SQL/CLI)

- ISO/IEC 9075-4 Persistent Stored Modules (SQL/PSM)

- ISO/IEC 9075-9 Management of External Data (SQL/MED)

- ISO/IEC 9075-10 Object Language Bindings (SQL/OLB)

- ISO/IEC 9075-11 Information and Definition Schemas (SQL/Schemata)

- ISO/IEC 9075-13 Routines and Types using the Java Language (SQL/JRT)

- ISO/IEC 9075-14 XML-related specifications (SQL/XML)

PostgreSQL covers parts 1, 2, and 11. Part 3 is similar to the ODBC interface, and part 4 is similar to the PL/pgSQL programming language, but exact conformance is not specifically intended or verified in either case.

PostgreSQL supports most of the major features of SQL:2003. Out of 164 mandatory features required for full Core conformance, PostgreSQL conforms to at least 150. In addition, there is a long list of supported optional features. It may be worth noting that at the time of writing, no current version of any database management system claims full conformance to Core SQL:2003.

In the following two sections, we provide a list of those features that PostgreSQL supports, followed by a list of the features defined in SQL:2003 which are not yet supported in PostgreSQL. Both of these lists are approximate: There may be minor details that are nonconforming for a feature that is listed as supported, and large parts of an unsupported feature may in fact be implemented. The main body of the documentation always contains the most accurate information about what does and does not work.

### Note

Feature codes containing a hyphen are subfeatures. Therefore, if a particular subfeature is not supported, the main feature is listed as unsupported even if some other subfeatures are supported.

## D.1. Supported Features

Identifier | Package | Description | Comment
--- | --- | --- | ---
B012 |  | Embedded C |
B021 |  | Direct SQL |
E011 | Core | Numeric data types |
E011-01 | Core | INTEGER and SMALLINT data types |
E011-02 | Core | REAL, DOUBLE PRECISION, and FLOAT data types |
E011-03 | Core | DECIMAL and NUMERIC data types |
E011-04 | Core | Arithmetic operators |
E011-05 | Core | Numeric comparison |
E011-06 | Core | Implicit casting among the numeric data types |
E021 | Core | Character data types |
E021-01 | Core | CHARACTER data type |
E021-02 | Core | CHARACTER VARYING data type |
E021-03 | Core | Character literals |
E021-04 | Core | CHARACTER_LENGTH function | trims trailing spaces from CHARACTER values before counting
E021-05 | Core | OCTET_LENGTH function |
E021-06 | Core | SUBSTRING function |
E021-07 | Core | Character concatenation |
E021-08 | Core | UPPER and LOWER functions |
E021-09 | Core | TRIM function |
E021-10 | Core | Implicit casting among the character string types |
E021-11 | Core | POSITION function |
E021-12 | Core | Character comparison |
E031 | Core | Identifiers |
E031-01 | Core | Delimited identifiers |
E031-02 | Core | Lower case identifiers |
E031-03 | Core | Trailing underscore |
E051 | Core | Basic query specification |
E051-01 | Core | SELECT DISTINCT |
E051-02 | Core | GROUP BY clause |
E051-04 | Core | GROUP BY can contain columns not in <select list> |
E051-05 | Core | Select list items can be renamed | AS is required
E051-06 | Core | HAVING clause |
E051-07 | Core | Qualified * in select list |
E051-08 | Core | Correlation names in the FROM clause |
E051-09 | Core | Rename columns in the FROM clause |
E061 | Core | Basic predicates and search conditions |
E061-01 | Core | Comparison predicate |
E061-02 | Core | BETWEEN predicate |
E061-03 | Core | IN predicate with list of values |
E061-04 | Core | LIKE predicate |
E061-05 | Core | LIKE predicate ESCAPE clause |
E061-06 | Core | NULL predicate |
E061-07 | Core | Quantified comparison predicate |
E061-08 | Core | EXISTS predicate |
E061-09 | Core | Subqueries in comparison predicate |
E061-11 | Core | Subqueries in IN predicate |
E061-12 | Core | Subqueries in quantified comparison predicate |
E061-13 | Core | Correlated subqueries |
E061-14 | Core | Search condition |
E071 | Core | Basic query expressions |
E071-01 | Core | UNION DISTINCT table operator |
E071-02 | Core | UNION ALL table operator |
E071-03 | Core | EXCEPT DISTINCT table operator |
E071-05 | Core | Columns combined via table operators need not have exactly the same data type |
E071-06 | Core | Table operators in subqueries |
E081-01 | Core | SELECT privilege |
E081-02 | Core | DELETE privilege |
E081-03 | Core | INSERT privilege at the table level |
E081-04 | Core | UPDATE privilege at the table level |
E081-06 | Core | REFERENCES privilege at the table level |
E081-08 | Core | WITH GRANT OPTION |
E081-10 | Core | EXECUTE privilege |
E091 | Core | Set functions |
E091-01 | Core | AVG |
E091-02 | Core | COUNT |
E091-03 | Core | MAX |
E091-04 | Core | MIN |
E091-05 | Core | SUM |
E091-06 | Core | ALL quantifier |
E091-07 | Core | DISTINCT quantifier |
E101 | Core | Basic data manipulation |
E101-01 | Core | INSERT statement |
E101-03 | Core | Searched UPDATE statement |
E101-04 | Core | Searched DELETE statement |
E111 | Core | Single row SELECT statement |
E121-01 | Core | DECLARE CURSOR |
E121-02 | Core | ORDER BY columns need not be in select list |
E121-03 | Core | Value expressions in ORDER BY clause |
E121-04 | Core | OPEN statement |
E121-08 | Core | CLOSE statement |
E121-10 | Core | FETCH statement implicit NEXT |
E121-17 | Core | WITH HOLD cursors |
E131 | Core | Null value support (nulls in lieu of values) |
E141 | Core | Basic integrity constraints |
E141-01 | Core | NOT NULL constraints |
E141-02 | Core | UNIQUE constraints of NOT NULL columns |
E141-03 | Core | PRIMARY KEY constraints |
E141-04 | Core | Basic FOREIGN KEY constraint with the NO ACTION default for both referential delete action and referential update action |
E141-06 | Core | CHECK constraints |
E141-07 | Core | Column defaults |
E141-08 | Core | NOT NULL inferred on PRIMARY KEY |
E141-10 | Core | Names in a foreign key can be specified in any order |
E151 | Core | Transaction support |
E151-01 | Core | COMMIT statement |
E151-02 | Core | ROLLBACK statement |
E152 | Core | Basic SET TRANSACTION statement |
E152-01 | Core | SET TRANSACTION statement: ISOLATION LEVEL SERIALIZABLE clause |
E152-02 | Core | SET TRANSACTION statement: READ ONLY and READ WRITE clauses |
E161 | Core | SQL comments using leading double minus |
E171 | Core | SQLSTATE support |
F021 | Core | Basic information schema |
F021-01 | Core | COLUMNS view |
F021-02 | Core | TABLES view |
F021-03 | Core | VIEWS view |
F021-04 | Core | TABLE_CONSTRAINTS view |
F021-05 | Core | REFERENTIAL_CONSTRAINTS view |
F021-06 | Core | CHECK_CONSTRAINTS view |
F031 | Core | Basic schema manipulation |
F031-01 | Core | CREATE TABLE statement to create persistent base tables |
F031-02 | Core | CREATE VIEW statement |
F031-03 | Core | GRANT statement |
F031-04 | Core | ALTER TABLE statement: ADD COLUMN clause |
F031-13 | Core | DROP TABLE statement: RESTRICT clause |
F031-16 | Core | DROP VIEW statement: RESTRICT clause |
F031-19 | Core | REVOKE statement: RESTRICT clause |
F032 |  | CASCADE drop behavior |
F033 |  | ALTER TABLE statement: DROP COLUMN clause |
F034 |  | Extended REVOKE statement |
F034-01 |  | REVOKE statement performed by other than the owner of a schema object |
F034-02 |  | REVOKE statement: GRANT OPTION FOR clause |
F034-03 |  | REVOKE statement to revoke a privilege that the grantee has WITH GRANT OPTION |
F041 | Core | Basic joined table |
F041-01 | Core | Inner join (but not necessarily the INNER keyword) |
F041-02 | Core | INNER keyword |
F041-03 | Core | LEFT OUTER JOIN |
F041-04 | Core | RIGHT OUTER JOIN |
F041-05 | Core | Outer joins can be nested |
F041-07 | Core | The inner table in a left or right outer join can also be used in an inner join |
F041-08 | Core | All comparison operators are supported (rather than just =) |
F051 | Core | Basic date and time |
F051-01 | Core | DATE data type (including support of DATE literal) |
F051-02 | Core | TIME data type (including support of TIME literal) with fractional seconds precision of at least 0 |
F051-03 | Core | TIMESTAMP data type (including support of TIMESTAMP literal) with fractional seconds precision of at least 0 and 6 |
F051-04 | Core | Comparison predicate on DATE, TIME, and TIMESTAMP data types |
F051-05 | Core | Explicit CAST between datetime types and character string types |
F051-06 | Core | CURRENT_DATE |
F051-07 | Core | LOCALTIME |
F051-08 | Core | LOCALTIMESTAMP |
F052 | Enhanced datetime facilities | Intervals and datetime arithmetic |
F053 |  | OVERLAPS predicate |
F081 | Core | UNION and EXCEPT in views |
F111 |  | Isolation levels other than SERIALIZABLE |
F111-01 |  | READ UNCOMMITTED isolation level |
F111-02 |  | READ COMMITTED isolation level |
F111-03 |  | REPEATABLE READ isolation level |
F131 | Core | Grouped operations |
F131-01 | Core | WHERE, GROUP BY, and HAVING clauses supported in queries with grouped views |
F131-02 | Core | Multiple tables supported in queries with grouped views |
F131-03 | Core | Set functions supported in queries with grouped views |
F131-04 | Core | Subqueries with GROUP BY and HAVING clauses and grouped views |
F131-05 | Core | Single row SELECT with GROUP BY and HAVING clauses and grouped views |
F171 |  | Multiple schemas per user |
F191 | Enhanced integrity management | Referential delete actions |
F201 | Core | CAST function |
F221 | Core | Explicit defaults |
F222 |  | INSERT statement: DEFAULT VALUES clause |
F231 |  | Privilege tables |
F231-01 |  | TABLE_PRIVILEGES view |
F231-02 |  | COLUMN_PRIVILEGES view |
F231-03 |  | USAGE_PRIVILEGES view |
F251 |  | Domain support |
F261 | Core | CASE expression |
F261-01 | Core | Simple CASE |
F261-02 | Core | Searched CASE |
F261-03 | Core | NULLIF |
F261-04 | Core | COALESCE |
F271 |  | Compound character literals |
F281 |  | LIKE enhancements |
F302 |  | INTERSECT table operator |
F302-01 |  | INTERSECT DISTINCT table operator |
F302-02 |  | INTERSECT ALL table operator |
F304 |  | EXCEPT ALL table operator |
F311-01 | Core | CREATE SCHEMA |
F311-02 | Core | CREATE TABLE for persistent base tables |
F311-03 | Core | CREATE VIEW |
F311-05 | Core | GRANT statement |
F321 |  | User authorization |
F361 |  | Subprogram support |
F381 |  | Extended schema manipulation |
F381-01 |  | ALTER TABLE statement: ALTER COLUMN clause |
F381-02 |  | ALTER TABLE statement: ADD CONSTRAINT clause |
F381-03 |  | ALTER TABLE statement: DROP CONSTRAINT clause |
F391 |  | Long identifiers |
F401 |  | Extended joined table |
F401-01 |  | NATURAL JOIN |
F401-02 |  | FULL OUTER JOIN |
F401-04 |  | CROSS JOIN |
F411 | Enhanced datetime facilities | Time zone specification | differences regarding literal interpretation
F421 |  | National character |
F431 |  | Read-only scrollable cursors |
F431-01 |  | FETCH with explicit NEXT |
F431-02 |  | FETCH FIRST |
F431-03 |  | FETCH LAST |
F431-04 |  | FETCH PRIOR |
F431-05 |  | FETCH ABSOLUTE |
F431-06 |  | FETCH RELATIVE |
F441 |  | Extended set function support |
F471 | Core | Scalar subquery values |
F481 | Core | Expanded NULL predicate |
F491 | Enhanced integrity management | Constraint management |
F501 | Core | Features and conformance views |
F501-01 | Core | SQL_FEATURES view |
F501-02 | Core | SQL_SIZING view |
F501-03 | Core | SQL_LANGUAGES view |
F502 |  | Enhanced documentation tables |
F502-01 |  | SQL_SIZING_PROFILES view |
F502-02 |  | SQL_IMPLEMENTATION_INFO view |
F502-03 |  | SQL_PACKAGES view |
F531 |  | Temporary tables |
F555 | Enhanced datetime facilities | Enhanced seconds precision |
F561 |  | Full value expressions |
F571 |  | Truth value tests |
F591 |  | Derived tables |
F611 |  | Indicator data types |
F651 |  | Catalog name qualifiers |
F672 |  | Retrospective check constraints |
F701 | Enhanced integrity management | Referential update actions |
F711 |  | ALTER domain |
F761 |  | Session management |
F771 |  | Connection management |
F781 |  | Self-referencing operations |
F791 |  | Insensitive cursors |
F801 |  | Full set function |
S071 | Enhanced object support | SQL paths in function and type name resolution |
S111 | Enhanced object support | ONLY in query expressions |
S211 | Enhanced object support | User-defined cast functions |
T031 |  | BOOLEAN data type |
T071 |  | BIGINT data type |
T141 |  | SIMILAR predicate |
T151 |  | DISTINCT predicate |
T171 |  | LIKE clause in table definition |
T191 | Enhanced integrity management | Referential action RESTRICT |
T201 | Enhanced integrity management | Comparable data types for referential constraints |
T211-01 | Active database, Enhanced integrity management | Triggers activated on UPDATE, INSERT, or DELETE of one base table |
T211-02 | Active database, Enhanced integrity management | BEFORE triggers |
T211-03 | Active database, Enhanced integrity management | AFTER triggers |
T211-04 | Active database, Enhanced integrity management | FOR EACH ROW triggers |
T211-07 | Active database, Enhanced integrity management | TRIGGER privilege |
T212 | Enhanced integrity management | Enhanced trigger capability |
T231 |  | Sensitive cursors |
T241 |  | START TRANSACTION statement |
T271 |  | Savepoints |
T312 |  | OVERLAY function |
T321-01 | Core | User-defined functions with no overloading |
T321-03 | Core | Function invocation |
T321-06 | Core | ROUTINES view |
T321-07 | Core | PARAMETERS view |
T322 | PSM | Overloading of SQL-invoked functions and procedures |
T323 |  | Explicit security for external routines |
T351 |  | Bracketed SQL comments (/*...*/ comments) |
T441 |  | ABS and MOD functions |
T461 |  | Symmetric BETWEEN predicate |
T501 |  | Enhanced EXISTS predicate |
T551 |  | Optional key words for default syntax |
T581 |  | Regular expression substring function |
T591 |  | UNIQUE constraints of possibly null columns |