mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-10 09:32:06 +00:00
57 KiB
57 KiB
| sidebar_position | sidebar_label |
|---|---|
| 40 | ANSI Compatibility |
ANSI SQL Compatibility of ClickHouse SQL Dialect
:::note
This article relies on Table 38, “Feature taxonomy and definition for mandatory features”, Annex F of ISO/IEC CD 9075-2:2011.
:::
Differences in Behaviour
The following table lists cases when query feature works in ClickHouse, but behaves not as specified in ANSI SQL.
| Feature ID | Feature Name | Difference |
|---|---|---|
| E011 | Numeric data types | Numeric literal with period is interpreted as approximate (Float64) instead of exact (Decimal) |
| E051-05 | Select items can be renamed | Item renames have a wider visibility scope than just the SELECT result |
| E141-01 | NOT NULL constraints | NOT NULL is implied for table columns by default |
| E011-04 | Arithmetic operators | ClickHouse overflows instead of checked arithmetic and changes the result data type based on custom rules |
Feature Status
| Feature ID | Feature Name | Status | Comment |
|---|---|---|---|
| E011 | Numeric data types | Partial | |
| E011-01 | INTEGER and SMALLINT data types | Yes | |
| E011-02 | REAL, DOUBLE PRECISION and FLOAT data types data types | Yes | |
| E011-03 | DECIMAL and NUMERIC data types | Yes | |
| E011-04 | Arithmetic operators | Yes | |
| E011-05 | Numeric comparison | Yes | |
| E011-06 | Implicit casting among the numeric data types | No | ANSI SQL allows arbitrary implicit cast between numeric types, while ClickHouse relies on functions having multiple overloads instead of implicit cast |
| E021 | Character string types | Partial | |
| E021-01 | CHARACTER data type | Yes | |
| E021-02 | CHARACTER VARYING data type | Yes | |
| E021-03 | Character literals | Yes | |
| E021-04 | CHARACTER_LENGTH function | Partial | No USING clause |
| E021-05 | OCTET_LENGTH function | No | LENGTH behaves similarly |
| E021-06 | SUBSTRING | Partial | No support for SIMILAR and ESCAPE clauses, no SUBSTRING_REGEX variant |
| E021-07 | Character concatenation | Partial | No COLLATE clause |
| E021-08 | UPPER and LOWER functions | Yes | |
| E021-09 | TRIM function | Yes | |
| E021-10 | Implicit casting among the fixed-length and variable-length character string types | Partial | ANSI SQL allows arbitrary implicit cast between string types, while ClickHouse relies on functions having multiple overloads instead of implicit cast |
| E021-11 | POSITION function | Partial | No support for IN and USING clauses, no POSITION_REGEX variant |
| E021-12 | Character comparison | Yes | |
| E031 | Identifiers | Partial | |
| E031-01 | Delimited identifiers | Partial | Unicode literal support is limited |
| E031-02 | Lower case identifiers | Yes | |
| E031-03 | Trailing underscore | Yes | |
| E051 | Basic query specification | Partial | |
| E051-01 | SELECT DISTINCT | Yes | |
| E051-02 | GROUP BY clause | Yes | |
| E051-04 | GROUP BY can contain columns not in <select list> |
Yes | |
| E051-05 | Select items can be renamed | Yes | |
| E051-06 | HAVING clause | Yes | |
| E051-07 | Qualified * in select list | Yes | |
| E051-08 | Correlation name in the FROM clause | Yes | |
| E051-09 | Rename columns in the FROM clause | No | |
| E061 | Basic predicates and search conditions | Partial | |
| E061-01 | Comparison predicate | Yes | |
| E061-02 | BETWEEN predicate | Partial | No SYMMETRIC and ASYMMETRIC clause |
| E061-03 | IN predicate with list of values | Yes | |
| E061-04 | LIKE predicate | Yes | |
| E061-05 | LIKE predicate: ESCAPE clause | No | |
| E061-06 | NULL predicate | Yes | |
| E061-07 | Quantified comparison predicate | No | |
| E061-08 | EXISTS predicate | No | |
| E061-09 | Subqueries in comparison predicate | Yes | |
| E061-11 | Subqueries in IN predicate | Yes | |
| E061-12 | Subqueries in quantified comparison predicate | No | |
| E061-13 | Correlated subqueries | No | |
| E061-14 | Search condition | Yes | |
| E071 | Basic query expressions | Partial | |
| E071-01 | UNION DISTINCT table operator | Yes | |
| E071-02 | UNION ALL table operator | Yes | |
| E071-03 | EXCEPT DISTINCT table operator | No | |
| E071-05 | Columns combined via table operators need not have exactly the same data type | Yes | |
| E071-06 | Table operators in subqueries | Yes | |
| E081 | Basic privileges | Yes | |
| E081-01 | SELECT privilege at the table level | Yes | |
| E081-02 | DELETE privilege | ||
| E081-03 | INSERT privilege at the table level | Yes | |
| E081-04 | UPDATE privilege at the table level | Yes | |
| E081-05 | UPDATE privilege at the column level | ||
| E081-06 | REFERENCES privilege at the table level | ||
| E081-07 | REFERENCES privilege at the column level | ||
| E081-08 | WITH GRANT OPTION | Yes | |
| E081-09 | USAGE privilege | ||
| E081-10 | EXECUTE privilege | ||
| E091 | Set functions | Yes | |
| E091-01 | AVG | Yes | |
| E091-02 | COUNT | Yes | |
| E091-03 | MAX | Yes | |
| E091-04 | MIN | Yes | |
| E091-05 | SUM | Yes | |
| E091-06 | ALL quantifier | Yes | |
| E091-07 | DISTINCT quantifier | Yes | Not all aggregate functions supported |
| E101 | Basic data manipulation | Partial | |
| E101-01 | INSERT statement | Yes | Note: primary key in ClickHouse does not imply the UNIQUE constraint |
| E101-03 | Searched UPDATE statement | Partial | There’s an ALTER UPDATE statement for batch data modification |
| E101-04 | Searched DELETE statement | Partial | There’s an ALTER DELETE statement for batch data removal |
| E111 | Single row SELECT statement | No | |
| E121 | Basic cursor support | No | |
| E121-01 | DECLARE CURSOR | No | |
| E121-02 | ORDER BY columns need not be in select list | Yes | |
| E121-03 | Value expressions in ORDER BY clause | Yes | |
| E121-04 | OPEN statement | No | |
| E121-06 | Positioned UPDATE statement | No | |
| E121-07 | Positioned DELETE statement | No | |
| E121-08 | CLOSE statement | No | |
| E121-10 | FETCH statement: implicit NEXT | No | |
| E121-17 | WITH HOLD cursors | No | |
| E131 | Null value support (nulls in lieu of values) | Yes | Some restrictions apply |
| E141 | Basic integrity constraints | Partial | |
| E141-01 | NOT NULL constraints | Yes | Note: NOT NULL is implied for table columns by default |
| E141-02 | UNIQUE constraint of NOT NULL columns | No | |
| E141-03 | PRIMARY KEY constraints | Partial | |
| E141-04 | Basic FOREIGN KEY constraint with the NO ACTION default for both referential delete action and referential update action | No | |
| E141-06 | CHECK constraint | Yes | |
| E141-07 | Column defaults | Yes | |
| E141-08 | NOT NULL inferred on PRIMARY KEY | Yes | |
| E141-10 | Names in a foreign key can be specified in any order | No | |
| E151 | Transaction support | No | |
| E151-01 | COMMIT statement | No | |
| E151-02 | ROLLBACK statement | No | |
| E152 | Basic SET TRANSACTION statement | No | |
| E152-01 | SET TRANSACTION statement: ISOLATION LEVEL SERIALIZABLE clause | No | |
| E152-02 | SET TRANSACTION statement: READ ONLY and READ WRITE clauses | No | |
| E153 | Updatable queries with subqueries | Yes | |
| E161 | SQL comments using leading double minus | Yes | |
| E171 | SQLSTATE support | No | |
| E182 | Host language binding | No | |
| F031 | Basic schema manipulation | Partial | |
| F031-01 | CREATE TABLE statement to create persistent base tables | Partial | No SYSTEM VERSIONING, ON COMMIT, GLOBAL, LOCAL, PRESERVE, DELETE, REF IS, WITH OPTIONS, UNDER, LIKE, PERIOD FOR clauses and no support for user resolved data types |
| F031-02 | CREATE VIEW statement | Partial | No RECURSIVE, CHECK, UNDER, WITH OPTIONS clauses and no support for user resolved data types |
| F031-03 | GRANT statement | Yes | |
| F031-04 | ALTER TABLE statement: ADD COLUMN clause | Yes | No support for GENERATED clause and system time period |
| F031-13 | DROP TABLE statement: RESTRICT clause | No | |
| F031-16 | DROP VIEW statement: RESTRICT clause | No | |
| F031-19 | REVOKE statement: RESTRICT clause | No | |
| F041 | Basic joined table | Partial | |
| F041-01 | Inner join (but not necessarily the INNER keyword) | Yes | |
| F041-02 | INNER keyword | Yes | |
| F041-03 | LEFT OUTER JOIN | Yes | |
| F041-04 | RIGHT OUTER JOIN | Yes | |
| F041-05 | Outer joins can be nested | Yes | |
| F041-07 | The inner table in a left or right outer join can also be used in an inner join | Yes | |
| F041-08 | All comparison operators are supported (rather than just =) | No | |
| F051 | Basic date and time | Partial | |
| F051-01 | DATE data type (including support of DATE literal) | Yes | |
| F051-02 | TIME data type (including support of TIME literal) with fractional seconds precision of at least 0 | No | |
| F051-03 | TIMESTAMP data type (including support of TIMESTAMP literal) with fractional seconds precision of at least 0 and 6 | Yes | |
| F051-04 | Comparison predicate on DATE, TIME, and TIMESTAMP data types | Yes | |
| F051-05 | Explicit CAST between datetime types and character string types | Yes | |
| F051-06 | CURRENT_DATE | No | today() is similar |
| F051-07 | LOCALTIME | No | now() is similar |
| F051-08 | LOCALTIMESTAMP | No | |
| F081 | UNION and EXCEPT in views | Partial | |
| F131 | Grouped operations | Partial | |
| F131-01 | WHERE, GROUP BY, and HAVING clauses supported in queries with grouped views | Yes | |
| F131-02 | Multiple tables supported in queries with grouped views | Yes | |
| F131-03 | Set functions supported in queries with grouped views | Yes | |
| F131-04 | Subqueries with GROUP BY and HAVING clauses and grouped views | Yes | |
| F131-05 | Single row SELECT with GROUP BY and HAVING clauses and grouped views | No | |
| F181 | Multiple module support | No | |
| F201 | CAST function | Yes | |
| F221 | Explicit defaults | No | |
| F261 | CASE expression | Yes | |
| F261-01 | Simple CASE | Yes | |
| F261-02 | Searched CASE | Yes | |
| F261-03 | NULLIF | Yes | |
| F261-04 | COALESCE | Yes | |
| F311 | Schema definition statement | Partial | |
| F311-01 | CREATE SCHEMA | Partial | See CREATE DATABASE |
| F311-02 | CREATE TABLE for persistent base tables | Yes | |
| F311-03 | CREATE VIEW | Yes | |
| F311-04 | CREATE VIEW: WITH CHECK OPTION | No | |
| F311-05 | GRANT statement | Yes | |
| F471 | Scalar subquery values | Yes | |
| F481 | Expanded NULL predicate | Yes | |
| F812 | Basic flagging | No | |
| S011 | Distinct data types | ||
| T321 | Basic SQL-invoked routines | No | |
| T321-01 | User-defined functions with no overloading | No | |
| T321-02 | User-defined stored procedures with no overloading | No | |
| T321-03 | Function invocation | No | |
| T321-04 | CALL statement | No | |
| T321-05 | RETURN statement | No | |
| T631 | IN predicate with one list element | Yes |