历史版本。 PostgreSQL 8.0 已结束支持。 请参阅 当前版本手册.
附录 D. SQL 符合性
本节尝试概述PostgreSQL在多大程度上符合当前的 SQL 标准。下文并不是一份完整的符合性声明，但会在合理且对用户有用的范围内，尽可能详细地介绍主要主题。
SQL 标准的正式名称是 ISO/IEC 9075“数据库语言 SQL”。该标准不时发布修订版本；最近一次发布于 2003 年末。该版本称为 ISO/IEC 9075:2003，或简称 SQL:2003。在此之前的版本是 SQL:1999 和 SQL-92。每个版本都取代前一个版本，因此声称符合早期版本并没有官方意义。PostgreSQL的开发目标是在不与传统特性或常识相矛盾的前提下，符合该标准的最新官方版本。在 SQL:2003 的制定期间，PostgreSQL 项目并未参与 ISO/IEC 9075 工作组。即便如此，SQL:2003 所要求的许多特性已经得到支持，尽管有时语法或功能略有差异。可以预期在后续版本中会进一步向标准靠拢。
SQL-92为符合性定义了三个特性集：入门（Entry）、中级（Intermediate）和完整（Full）。多数宣称符合SQL标准的数据库管理系统，实际上只符合入门（Entry）级别，因为中级（Intermediate）和完整（Full）级别中的全部特性要么过于庞杂，要么与既有行为相冲突。
从SQL:1999开始，SQL 标准不再沿用SQL-92中那种效果不佳且过于宽泛的三级分类，而是定义了大量独立特性。其中很大一个子集构成了核心（“Core”）特性，也就是每个符合 SQL 标准的实现都必须提供的特性。其余特性则完全是可选的。某些可选特性被组合在一起，形成“包”，SQL 实现可以声明符合这些包，从而表明符合特定的特性组。
SQL:2003标准也分为若干部分，每部分都有一个简称。注意这些部分的编号并不连续。
ISO/IEC 9075-1 框架（SQL/Framework）
ISO/IEC 9075-2 基础（SQL/Foundation）
ISO/IEC 9075-3 调用级接口（SQL/CLI）
ISO/IEC 9075-4 持久存储模块（SQL/PSM）
ISO/IEC 9075-9 外部数据管理（SQL/MED）
ISO/IEC 9075-10 对象语言绑定（SQL/OLB）
ISO/IEC 9075-11 信息和定义模式（SQL/Schemata）
ISO/IEC 9075-13 使用 Java 语言的例程和类型（SQL/JRT）
ISO/IEC 9075-14 XML 相关规范（SQL/XML）
PostgreSQL涵盖第 1、2 和 11 部分。第 3 部分类似于 ODBC 接口，第 4 部分类似于 PL/pgSQL编程语言，但在两种情况下都未专门意图或核验确切符合性。
PostgreSQL 支持 SQL:2003 的大部分主要特性。在完全符合 Core 所要求的 164 个强制特性中，PostgreSQL 至少符合 150 个。此外，还有一长串受支持的可选特性。值得注意的是，截至撰写时，尚无任何数据库管理系统的当前版本声称完全符合 Core SQL:2003。
在下面两节中，我们先列出PostgreSQL支持的特性，然后列出SQL:2003中定义但PostgreSQL尚不支持的特性。这两个列表都是近似的：被列为受支持的特性可能存在个别不符合标准的细节，而不受支持的特性也可能实际上已实现了很大一部分。关于什么可用什么不可用的最准确信息，始终以文档正文为准。
注意
带连字符的特性代码表示子特性。因此，如果某个特定子特性不受支持，则即使该主特性的其他子特性受支持，该主特性也会被列为不受支持。
D.1. 支持的特性 #
| 标识符 | 包 | 描述 | 注释 |
|---|---|---|---|
| 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 | ||
| T501 | Enhanced EXISTS predicate | ||
| T551 | Optional key words for default syntax | ||
| T581 | Regular expression substring function | ||
| T591 | UNIQUE constraints of possibly null columns |