diff --git a/content/docs-lite/zh/docs/SQLReference/SELECT.md b/content/docs-lite/zh/docs/SQLReference/SELECT.md index baaed85676c7a30e768aebdf54395619ebd55ce9..cc1128cc82ea450963ff2fcbfee7139ba31ab34e 100644 --- a/content/docs-lite/zh/docs/SQLReference/SELECT.md +++ b/content/docs-lite/zh/docs/SQLReference/SELECT.md @@ -90,9 +90,21 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] |function_name ( [ argument [, ...] ] ) [ AS ] alias [ ( column_alias [, ...] | column_definition [, ...] ) ] |function_name ( [ argument [, ...] ] ) AS ( column_definition [, ...] ) |from_item [ NATURAL ] join_type from_item [ ON join_condition | USING ( join_column [, ...] ) ] - |rotate_clause - |notrotate_clause} - ``` + |rotate_clause + |notrotate_clause + |lateral lateral_subquery [ AS ] alias + |from_item cross apply lateral_subquery [ AS ] alias + |from_item outer apply lateral_subquery [ AS ] alias} + ``` +- 其中lateral_subquery的字句为： + + ``` + table + | subquery + | function_name ( [ argument [, ...] ] ) + ``` + + lateral_subquery和普通的subquery的区别在于lateral_subquery可以引用跨路径的变量（如上层路径的列数据），普通的subquery不行。 - 其中group子句为： @@ -219,7 +231,7 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] 指定文件的绝对路径。 ``` - into_option三处位置： + into_option三处位置： --在from子句之前。 openGauss=# select * into @my_var from t; --在锁定子句之前。 @@ -239,57 +251,58 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] --导出数据到dumpfile文件。 openGauss=# select * from t into dumpfile '/home/openGauss/t.txt'; 文件内容：1a - ``` - -- **FROM子句** + ``` + +- **FROM子句** - 为SELECT声明一个或者多个源表。 + 为SELECT声明一个或者多个源表。 - FROM子句涉及的元素如下所示。 + FROM子句涉及的元素如下所示。 - - table\_name + - table\_name - 表名或视图名，名称前可加上模式名，如：schema\_name.table\_name。 + 表名或视图名，名称前可加上模式名，如：schema\_name.table\_name。 - - alias + - alias - 给表或复杂的表引用起一个临时的表别名，以便被其余的查询引用。 + 给表或复杂的表引用起一个临时的表别名，以便被其余的查询引用。 - 别名用于缩写或者在自连接中消除歧义。如果提供了别名，它就会完全隐藏表的实际名称。 + 别名用于缩写或者在自连接中消除歧义。如果提供了别名，它就会完全隐藏表的实际名称。 - - TABLESAMPLE _sampling\_method_ \( _argument_ \[, ...\] \) \[ REPEATABLE \( _seed_ \) \] + - TABLESAMPLE _sampling\_method_ \( _argument_ \[, ...\] \) \[ REPEATABLE \( _seed_ \) \] - _table\_name_ 之后的 TABLESAMPLE 子句表示应该用指定的 _sampling\_method_ 来检索表中行的子集。_sampling\_method_ 可以被指定为以下方法： - - bernoulli，按行采样。 - - system，按块(页)采样。 - - hybrid，混合采样，_argument_ 可以分别指定按行采样和按块(页)采样的百分比。 - - _argument_ 部分用来指定采样百分比，是一个非空数值表达式（如10或'10'），取值范围是`[0.000001,100)`。 + _table\_name_ 之后的 TABLESAMPLE 子句表示应该用指定的 _sampling\_method_ 来检索表中行的子集。_sampling\_method_ 可以被指定为以下方法： + - bernoulli，按行采样。 + - system，按块(页)采样。 + - hybrid，混合采样，_argument_ 可以分别指定按行采样和按块(页)采样的百分比。 + - 可选的 REPEATABLE 部分指定一个用于产生采样方法中随机数的种子值 _seed_，是一个非空数值表达式（如10或'10'），种子值的取值范围是`[0,4294967295]`。如果查询时表没有被更改，指定相同 _seed_ 和 _argument_ 值的两个查询将会选择该表相同的采样。但是不同的种子值通常将会产生不同的采样。如果没有给出 REPEATABLE，则会基于一个系统产生的种子为每一个查询选择一个新的随机采样。 + _argument_ 部分用来指定采样百分比，是一个非空数值表达式（如10或'10'），取值范围是`[0.000001,100)`。 - _table\_name_ 可以是普通表，分区表，普通视图，物化视图和键保留（key-preserved）的连接视图；普通视图指在单表上查询创建的视图；键保留的连接视图指对键保留表进行连接操作后创建的视图，但不支持对包含超过一个非键保留表的连接视图进行数据采样。 + 可选的 REPEATABLE 部分指定一个用于产生采样方法中随机数的种子值 _seed_，是一个非空数值表达式（如10或'10'），种子值的取值范围是`[0,4294967295]`。如果查询时表没有被更改，指定相同 _seed_ 和 _argument_ 值的两个查询将会选择该表相同的采样。但是不同的种子值通常将会产生不同的采样。如果没有给出 REPEATABLE，则会基于一个系统产生的种子为每一个查询选择一个新的随机采样。 - - TIMECAPSULE \{ TIMESTAMP | CSN \} expression + _table\_name_ 可以是普通表，分区表，普通视图，物化视图和键保留（key-preserved）的连接视图；普通视图指在单表上查询创建的视图；键保留的连接视图指对键保留表进行连接操作后创建的视图，但不支持对包含超过一个非键保留表的连接视图进行数据采样。 - 查询指定CSN点或者指定时间点表的内容。 + - TIMECAPSULE \{ TIMESTAMP | CSN \} expression - 目前不支持闪回查询的表：系统表、列存表、内存表、DFS表、全局临时表、本地临时表、UNLOGGED表、视图、序列表、hashbucket表、共享表、继承表、带有PARTIAL CLUSTER KEY约束的表。 + 查询指定CSN点或者指定时间点表的内容。 - - TIMECAPSULE TIMESTAMP + 目前不支持闪回查询的表：系统表、列存表、内存表、DFS表、全局临时表、本地临时表、UNLOGGED表、视图、序列表、hashbucket表、共享表、继承表、带有PARTIAL CLUSTER KEY约束的表。 - 关键字，闪回查询的标识，根据date日期，闪回查找指定时间点的结果集。date日期必须是一个过去有效的时间戳。 + - TIMECAPSULE TIMESTAMP - - TIMECAPSULE CSN + 关键字，闪回查询的标识，根据date日期，闪回查找指定时间点的结果集。date日期必须是一个过去有效的时间戳。 - 关键字，闪回查询的标识，根据表的CSN闪回查询指定CSN点的结果集。其中CSN可从gs\_txn\_snapshot记录的snpcsn号查得。 + - TIMECAPSULE CSN - >![](public_sys-resources/icon-note.gif) **说明：** - > - >- 闪回查询不能跨越影响表结构或物理存储的语句，否则会报错。即闪回点和当前点之间，如果执行过修改表结构或影响物理存储的语句（TRUNCATE、DDL、DCL、VACUUM FULL），则闪回失败。 - >- 闪回点过旧时，因闪回版本被回收等导致无法获取旧版本会导致闪回失败，报错：Restore point too old。可通过将[version_retention_age](../DatabaseReference/闪回相关参数.md#version_retention_age)和[vacuum_defer_cleanup_age](../DatabaseReference/闪回相关参数.md#vacuum_defer_cleanup_age)设置成同值，配置闪回功能旧版本保留期限，取值范围是0~1000000，值为0表示VACUUM不会延迟清除无效的行存记录。 - >- 通过时间方式指定闪回点，闪回数据和实际时间点最多偏差为3秒。 - >- 对表执行truncate之后，再进行闪回查询或者闪回表操作。通过时间点进行的闪回操作会报错：Snapshot too old。通过CSN进行的闪回操作会找不到数据，或者报错：Snapshot too old。 + 关键字，闪回查询的标识，根据表的CSN闪回查询指定CSN点的结果集。其中CSN可从gs\_txn\_snapshot记录的snpcsn号查得。 + + >![](public_sys-resources/icon-note.gif) **说明：** + > + >- 闪回查询不能跨越影响表结构或物理存储的语句，否则会报错。即闪回点和当前点之间，如果执行过修改表结构或影响物理存储的语句（TRUNCATE、DDL、DCL、VACUUM FULL），则闪回失败。 + >- 闪回点过旧时，因闪回版本被回收等导致无法获取旧版本会导致闪回失败，报错：Restore point too old。可通过将[version_retention_age](../DatabaseReference/闪回相关参数.md#version_retention_age)和[vacuum_defer_cleanup_age](../DatabaseReference/闪回相关参数.md#vacuum_defer_cleanup_age)设置成同值，配置闪回功能旧版本保留期限，取值范围是0~1000000，值为0表示VACUUM不会延迟清除无效的行存记录。 + >- 通过时间方式指定闪回点，闪回数据和实际时间点最多偏差为3秒。 + >- 对表执行truncate之后，再进行闪回查询或者闪回表操作。通过时间点进行的闪回操作会报错：Snapshot too old。通过CSN进行的闪回操作会找不到数据，或者报错：Snapshot too old。 - column\_alias @@ -1024,7 +1037,8 @@ set dolphin.sql_mode = ''; -- 所以当去重列与排序列的数据值没有一一对应时，可能会由于数据的插入顺序、数据量等不一致而导致最终输出结果不一样。 SELECT DISTINCT name FROM my_tbl ORDER BY score; ``` ---查询结果行列转换示例 +- 查询结果行列转换示例 + ``` --创建表original_orders openGauss=# create table original_orders (id int, year int, order_mode text, order_total int); @@ -1063,3 +1077,231 @@ openGauss=# select * from rotate_orders not rotate ( yearly_total for order_mode 2021 | online | 1000 (5 rows) ``` + +- lateral使用样例 + +``` +-- 创建表 +openGauss=# create table employees(employee_id int, department_id int, last_name varchar(50)); +CREATE TABLE +openGauss=# insert into departments values ('Marketing', 1); +INSERT 0 1 +openGauss=# insert into departments values ('Public Relations', 2); +INSERT 0 1 +openGauss=# insert into departments values ('Operations', 3); +INSERT 0 1 +openGauss=# insert into departments values ('Develop', 4); +INSERT 0 1 +openGauss=# insert into departments values ('Research', 5); +INSERT 0 1 +openGauss=# insert into departments values ('CEO', 6); +INSERT 0 1 +openGauss=# insert into departments values ('CFO', 7); +INSERT 0 1 +openGauss=# insert into employees values(1, 1, 'zhangsan1'); +INSERT 0 1 +openGauss=# insert into employees values(2, 1, 'zhangsan2'); +INSERT 0 1 +openGauss=# insert into employees values(3, 1, 'zhangsan3'); +INSERT 0 1 +openGauss=# insert into employees values(4, 1, 'zhangsan4'); +INSERT 0 1 +openGauss=# insert into employees values(5, 2, 'lisi1'); +INSERT 0 1 +openGauss=# insert into employees values(6, 2, 'lisi2'); +INSERT 0 1 +openGauss=# insert into employees values(7, 2, 'lisi3'); +INSERT 0 1 +openGauss=# insert into employees values(8, 2, 'lisi4'); +INSERT 0 1 +openGauss=# insert into employees values(9, 3, 'wangwu1'); +INSERT 0 1 +openGauss=# insert into employees values(10, 3, 'wangwu2'); +INSERT 0 1 +openGauss=# insert into employees values(11, 3, 'wangwu3'); +INSERT 0 1 +openGauss=# insert into employees values(12, 3, 'wangwu4'); +INSERT 0 1 +openGauss=# insert into employees values(13, 4, 'heliu1'); +INSERT 0 1 +openGauss=# insert into employees values(14, 4, 'heliu2'); +INSERT 0 1 +openGauss=# insert into employees values(15, 4, 'heliu3'); +INSERT 0 1 +openGauss=# insert into employees values(16, 4, 'heliu4'); +INSERT 0 1 +openGauss=# insert into employees values(17, 5, 'chenqi1'); +INSERT 0 1 +openGauss=# insert into employees values(18, 5, 'chenqi2'); +INSERT 0 1 +openGauss=# insert into employees values(19, 5, 'chenqi3'); +INSERT 0 1 +openGauss=# insert into employees values(20, 5, 'chenqi4'); +INSERT 0 1 + +-- 跨路径进行lateral +openGauss=# select * from departments d, lateral (select * from employees e WHERE e.department_id = d.department_id) x; + department_name | department_id | employee_id | department_id | last_name +------------------+---------------+-------------+---------------+----------- + Marketing | 1 | 4 | 1 | zhangsan4 + Marketing | 1 | 3 | 1 | zhangsan3 + Marketing | 1 | 2 | 1 | zhangsan2 + Marketing | 1 | 1 | 1 | zhangsan1 + Public Relations | 2 | 8 | 2 | lisi4 + Public Relations | 2 | 7 | 2 | lisi3 + Public Relations | 2 | 6 | 2 | lisi2 + Public Relations | 2 | 5 | 2 | lisi1 + Operations | 3 | 12 | 3 | wangwu4 + Operations | 3 | 11 | 3 | wangwu3 + Operations | 3 | 10 | 3 | wangwu2 + Operations | 3 | 9 | 3 | wangwu1 + Develop | 4 | 16 | 4 | heliu4 + Develop | 4 | 15 | 4 | heliu3 + Develop | 4 | 14 | 4 | heliu2 + Develop | 4 | 13 | 4 | heliu1 + Research | 5 | 20 | 5 | chenqi4 + Research | 5 | 19 | 5 | chenqi3 + Research | 5 | 18 | 5 | chenqi2 + Research | 5 | 17 | 5 | chenqi1 +(20 rows) + +-- latera function +openGauss=# select * from departments d, lateral generate_series(1,2) g; + department_name | department_id | g +------------------+---------------+--- + Marketing | 1 | 1 + Public Relations | 2 | 1 + Operations | 3 | 1 + Develop | 4 | 1 + Research | 5 | 1 + CEO | 6 | 1 + CFO | 7 | 1 + Marketing | 1 | 2 + Public Relations | 2 | 2 + Operations | 3 | 2 + Develop | 4 | 2 + Research | 5 | 2 + CEO | 6 | 2 + CFO | 7 | 2 +(14 rows) +``` + + + +- cross apply和outer apply使用样例 + +``` +-- 创建表 +openGauss=# create table employees(employee_id int, department_id int, last_name varchar(50)); +CREATE TABLE +openGauss=# insert into departments values ('Marketing', 1); +INSERT 0 1 +openGauss=# insert into departments values ('Public Relations', 2); +INSERT 0 1 +openGauss=# insert into departments values ('Operations', 3); +INSERT 0 1 +openGauss=# insert into departments values ('Develop', 4); +INSERT 0 1 +openGauss=# insert into departments values ('Research', 5); +INSERT 0 1 +openGauss=# insert into departments values ('CEO', 6); +INSERT 0 1 +openGauss=# insert into departments values ('CFO', 7); +INSERT 0 1 +openGauss=# insert into employees values(1, 1, 'zhangsan1'); +INSERT 0 1 +openGauss=# insert into employees values(2, 1, 'zhangsan2'); +INSERT 0 1 +openGauss=# insert into employees values(3, 1, 'zhangsan3'); +INSERT 0 1 +openGauss=# insert into employees values(4, 1, 'zhangsan4'); +INSERT 0 1 +openGauss=# insert into employees values(5, 2, 'lisi1'); +INSERT 0 1 +openGauss=# insert into employees values(6, 2, 'lisi2'); +INSERT 0 1 +openGauss=# insert into employees values(7, 2, 'lisi3'); +INSERT 0 1 +openGauss=# insert into employees values(8, 2, 'lisi4'); +INSERT 0 1 +openGauss=# insert into employees values(9, 3, 'wangwu1'); +INSERT 0 1 +openGauss=# insert into employees values(10, 3, 'wangwu2'); +INSERT 0 1 +openGauss=# insert into employees values(11, 3, 'wangwu3'); +INSERT 0 1 +openGauss=# insert into employees values(12, 3, 'wangwu4'); +INSERT 0 1 +openGauss=# insert into employees values(13, 4, 'heliu1'); +INSERT 0 1 +openGauss=# insert into employees values(14, 4, 'heliu2'); +INSERT 0 1 +openGauss=# insert into employees values(15, 4, 'heliu3'); +INSERT 0 1 +openGauss=# insert into employees values(16, 4, 'heliu4'); +INSERT 0 1 +openGauss=# insert into employees values(17, 5, 'chenqi1'); +INSERT 0 1 +openGauss=# insert into employees values(18, 5, 'chenqi2'); +INSERT 0 1 +openGauss=# insert into employees values(19, 5, 'chenqi3'); +INSERT 0 1 +openGauss=# insert into employees values(20, 5, 'chenqi4'); +INSERT 0 1 +openGauss=# create function fn_salar (departmentid int) returns table (employee_id int, department_id int, last_name varchar) language sql as 'select employee_id, department_id, concat(last_name,last_name) as last_name2 from employees WHERE department_id = departmentid'; +CREATE FUNCTION + +-- 跨路径cross apply +openGauss=# SELECT d.department_name, v.employee_id, v.last_name +openGauss-# FROM departments d CROSS APPLY (SELECT * FROM employees e WHERE e.department_id = d.department_id) v +openGauss-# WHERE d.department_name IN ('Marketing', 'Operations', 'Public Relations', 'CEO', 'CFO') +openGauss-# ORDER BY d.department_name, v.employee_id; + department_name | employee_id | last_name +------------------+-------------+----------- + Marketing | 1 | zhangsan1 + Marketing | 2 | zhangsan2 + Marketing | 3 | zhangsan3 + Marketing | 4 | zhangsan4 + Operations | 9 | wangwu1 + Operations | 10 | wangwu2 + Operations | 11 | wangwu3 + Operations | 12 | wangwu4 + Public Relations | 5 | lisi1 + Public Relations | 6 | lisi2 + Public Relations | 7 | lisi3 + Public Relations | 8 | lisi4 + +-- cross apply function +openGauss=# SELECT * FROM employees AS e outer APPLY fn_Salar(e.department_id) AS f limit 5;; + employee_id | department_id | last_name | employee_id | department_id | last_name +-------------+---------------+-----------+-------------+---------------+-------------------- + 1 | 1 | zhangsan1 | 1 | 1 | zhangsan1zhangsan1 + 1 | 1 | zhangsan1 | 2 | 1 | zhangsan2zhangsan2 + 1 | 1 | zhangsan1 | 3 | 1 | zhangsan3zhangsan3 + 1 | 1 | zhangsan1 | 4 | 1 | zhangsan4zhangsan4 + 2 | 1 | zhangsan2 | 1 | 1 | zhangsan1zhangsan1 +(5 rows) + +-- 跨路径outer apply +openGauss=# SELECT d.department_name, v.employee_id, v.last_name +openGauss-# FROM departments d OUTER APPLY (SELECT * FROM employees e WHERE e.department_id = d.department_id) v +openGauss-# WHERE d.department_name IN ('Marketing', 'Operations', 'Public Relations', 'CEO', 'CFO') +openGauss-# ORDER BY d.department_name, v.employee_id; + department_name | employee_id | last_name +------------------+-------------+----------- + CEO | | + CFO | | + Marketing | 1 | zhangsan1 + Marketing | 2 | zhangsan2 + Marketing | 3 | zhangsan3 + Marketing | 4 | zhangsan4 + Operations | 9 | wangwu1 + Operations | 10 | wangwu2 + Operations | 11 | wangwu3 + Operations | 12 | wangwu4 + Public Relations | 5 | lisi1 + Public Relations | 6 | lisi2 + Public Relations | 7 | lisi3 + Public Relations | 8 | lisi4 +(14 rows) +``` diff --git a/content/zh/docs/SQLReference/SELECT.md b/content/zh/docs/SQLReference/SELECT.md index 157c86b493ca696f9ebd92291c67d95d8cd96034..fff7e89cdfd197b946ebcbc8a3c93513116e9833 100644 --- a/content/zh/docs/SQLReference/SELECT.md +++ b/content/zh/docs/SQLReference/SELECT.md @@ -96,9 +96,21 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] |function_name ( [ argument [, ...] ] ) [ AS ] alias [ ( column_alias [, ...] | column_definition [, ...] ) ] |function_name ( [ argument [, ...] ] ) AS ( column_definition [, ...] ) |from_item [ NATURAL ] join_type from_item [ ON join_condition | USING ( join_column [, ...] ) ] - |rotate_clause - |notrotate_clause} - ``` + |rotate_clause + |notrotate_clause + |lateral lateral_subquery [ AS ] alias + |from_item cross apply lateral_subquery [ AS ] alias + |from_item outer apply lateral_subquery [ AS ] alias} + ``` +- 其中lateral_subquery的字句为： + + ``` + table + | subquery + | function_name ( [ argument [, ...] ] ) + ``` + + lateral_subquery和普通的subquery的区别在于lateral_subquery可以引用跨路径的变量（如上层路径的列数据），普通的subquery不行。 - 其中group子句为： @@ -221,14 +233,15 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] 指定文件的绝对路径。 ``` - into_option三处位置： + into_option三处位置： --在from子句之前。 openGauss=# select * into @my_var from t; --在锁定子句之前。 openGauss=# select * from t into @my_var for update; --在select语句结尾。 - openGauss=# select * from t for update into @my_var; + openGauss=# select * from t for update into @my_var; + 导出到文件： openGauss=# select * from t； a | b @@ -373,6 +386,7 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] - rotate_clause 用于实现将查询结果行转列输出。 + 其语法格式如下： rotate_clause : { ROTATE @@ -380,43 +394,43 @@ SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] [, aggregate_function ( expr ) [[AS] alias ] ] ... rotate_for_clause rotate_in_clause ) - } - - 该子句涉及的元素如下所示。 - - - ROTATE - - 用于实现将查询结果行转列的关键字。 - - - aggregate_function - - 使用的聚合函数名称。 - - - expr - - 聚合函数参数列表。 - - - alias - - 聚合操作别名。 - - - rotate_for_clause - - 用于做行转列的列名，其语法格式如下： - - rotate_for_clause: { - FOR { column | ( column [, column]... ) } - } - - - rotate_in_clause - - 用于做行转列的列中的参数，其语法格式如下： - - rotate_in_clause: { - IN ( { { expr | ( expr [, expr]... ) } [ [ AS] alias] } - [, { { expr | ( expr [, expr]... ) } [ [ AS] alias] }]... - ) - } + } + + 该子句涉及的元素如下所示。 + + - ROTATE + + 用于实现将查询结果行转列的关键字。 + + - aggregate_function + + 使用的聚合函数名称。 + + - expr + + 聚合函数参数列表。 + + - alias + + 聚合操作别名。 + + - rotate_for_clause + + 用于做行转列的列名，其语法格式如下： + + rotate_for_clause: { + FOR { column | ( column [, column]... ) } + } + + - rotate_in_clause + + 用于做行转列的列中的参数，其语法格式如下： + + rotate_in_clause: { + IN ( { { expr | ( expr [, expr]... ) } [ [ AS] alias] } + [, { { expr | ( expr [, expr]... ) } [ [ AS] alias] }]... + ) + } - notrotate_clause @@ -1060,4 +1074,232 @@ openGauss=# select * from rotate_orders not rotate ( yearly_total for order_mode 2020 | online | 1000 2021 | online | 1000 (5 rows) -``` \ No newline at end of file +``` + +- lateral使用样例 + +``` +-- 创建表 +openGauss=# create table employees(employee_id int, department_id int, last_name varchar(50)); +CREATE TABLE +openGauss=# insert into departments values ('Marketing', 1); +INSERT 0 1 +openGauss=# insert into departments values ('Public Relations', 2); +INSERT 0 1 +openGauss=# insert into departments values ('Operations', 3); +INSERT 0 1 +openGauss=# insert into departments values ('Develop', 4); +INSERT 0 1 +openGauss=# insert into departments values ('Research', 5); +INSERT 0 1 +openGauss=# insert into departments values ('CEO', 6); +INSERT 0 1 +openGauss=# insert into departments values ('CFO', 7); +INSERT 0 1 +openGauss=# insert into employees values(1, 1, 'zhangsan1'); +INSERT 0 1 +openGauss=# insert into employees values(2, 1, 'zhangsan2'); +INSERT 0 1 +openGauss=# insert into employees values(3, 1, 'zhangsan3'); +INSERT 0 1 +openGauss=# insert into employees values(4, 1, 'zhangsan4'); +INSERT 0 1 +openGauss=# insert into employees values(5, 2, 'lisi1'); +INSERT 0 1 +openGauss=# insert into employees values(6, 2, 'lisi2'); +INSERT 0 1 +openGauss=# insert into employees values(7, 2, 'lisi3'); +INSERT 0 1 +openGauss=# insert into employees values(8, 2, 'lisi4'); +INSERT 0 1 +openGauss=# insert into employees values(9, 3, 'wangwu1'); +INSERT 0 1 +openGauss=# insert into employees values(10, 3, 'wangwu2'); +INSERT 0 1 +openGauss=# insert into employees values(11, 3, 'wangwu3'); +INSERT 0 1 +openGauss=# insert into employees values(12, 3, 'wangwu4'); +INSERT 0 1 +openGauss=# insert into employees values(13, 4, 'heliu1'); +INSERT 0 1 +openGauss=# insert into employees values(14, 4, 'heliu2'); +INSERT 0 1 +openGauss=# insert into employees values(15, 4, 'heliu3'); +INSERT 0 1 +openGauss=# insert into employees values(16, 4, 'heliu4'); +INSERT 0 1 +openGauss=# insert into employees values(17, 5, 'chenqi1'); +INSERT 0 1 +openGauss=# insert into employees values(18, 5, 'chenqi2'); +INSERT 0 1 +openGauss=# insert into employees values(19, 5, 'chenqi3'); +INSERT 0 1 +openGauss=# insert into employees values(20, 5, 'chenqi4'); +INSERT 0 1 + +-- 跨路径进行lateral +openGauss=# select * from departments d, lateral (select * from employees e WHERE e.department_id = d.department_id) x; + department_name | department_id | employee_id | department_id | last_name +------------------+---------------+-------------+---------------+----------- + Marketing | 1 | 4 | 1 | zhangsan4 + Marketing | 1 | 3 | 1 | zhangsan3 + Marketing | 1 | 2 | 1 | zhangsan2 + Marketing | 1 | 1 | 1 | zhangsan1 + Public Relations | 2 | 8 | 2 | lisi4 + Public Relations | 2 | 7 | 2 | lisi3 + Public Relations | 2 | 6 | 2 | lisi2 + Public Relations | 2 | 5 | 2 | lisi1 + Operations | 3 | 12 | 3 | wangwu4 + Operations | 3 | 11 | 3 | wangwu3 + Operations | 3 | 10 | 3 | wangwu2 + Operations | 3 | 9 | 3 | wangwu1 + Develop | 4 | 16 | 4 | heliu4 + Develop | 4 | 15 | 4 | heliu3 + Develop | 4 | 14 | 4 | heliu2 + Develop | 4 | 13 | 4 | heliu1 + Research | 5 | 20 | 5 | chenqi4 + Research | 5 | 19 | 5 | chenqi3 + Research | 5 | 18 | 5 | chenqi2 + Research | 5 | 17 | 5 | chenqi1 +(20 rows) + +-- latera function +openGauss=# select * from departments d, lateral generate_series(1,2) g; + department_name | department_id | g +------------------+---------------+--- + Marketing | 1 | 1 + Public Relations | 2 | 1 + Operations | 3 | 1 + Develop | 4 | 1 + Research | 5 | 1 + CEO | 6 | 1 + CFO | 7 | 1 + Marketing | 1 | 2 + Public Relations | 2 | 2 + Operations | 3 | 2 + Develop | 4 | 2 + Research | 5 | 2 + CEO | 6 | 2 + CFO | 7 | 2 +(14 rows) +``` + + + +- cross apply和outer apply使用样例 + +``` +-- 创建表 +openGauss=# create table employees(employee_id int, department_id int, last_name varchar(50)); +CREATE TABLE +openGauss=# insert into departments values ('Marketing', 1); +INSERT 0 1 +openGauss=# insert into departments values ('Public Relations', 2); +INSERT 0 1 +openGauss=# insert into departments values ('Operations', 3); +INSERT 0 1 +openGauss=# insert into departments values ('Develop', 4); +INSERT 0 1 +openGauss=# insert into departments values ('Research', 5); +INSERT 0 1 +openGauss=# insert into departments values ('CEO', 6); +INSERT 0 1 +openGauss=# insert into departments values ('CFO', 7); +INSERT 0 1 +openGauss=# insert into employees values(1, 1, 'zhangsan1'); +INSERT 0 1 +openGauss=# insert into employees values(2, 1, 'zhangsan2'); +INSERT 0 1 +openGauss=# insert into employees values(3, 1, 'zhangsan3'); +INSERT 0 1 +openGauss=# insert into employees values(4, 1, 'zhangsan4'); +INSERT 0 1 +openGauss=# insert into employees values(5, 2, 'lisi1'); +INSERT 0 1 +openGauss=# insert into employees values(6, 2, 'lisi2'); +INSERT 0 1 +openGauss=# insert into employees values(7, 2, 'lisi3'); +INSERT 0 1 +openGauss=# insert into employees values(8, 2, 'lisi4'); +INSERT 0 1 +openGauss=# insert into employees values(9, 3, 'wangwu1'); +INSERT 0 1 +openGauss=# insert into employees values(10, 3, 'wangwu2'); +INSERT 0 1 +openGauss=# insert into employees values(11, 3, 'wangwu3'); +INSERT 0 1 +openGauss=# insert into employees values(12, 3, 'wangwu4'); +INSERT 0 1 +openGauss=# insert into employees values(13, 4, 'heliu1'); +INSERT 0 1 +openGauss=# insert into employees values(14, 4, 'heliu2'); +INSERT 0 1 +openGauss=# insert into employees values(15, 4, 'heliu3'); +INSERT 0 1 +openGauss=# insert into employees values(16, 4, 'heliu4'); +INSERT 0 1 +openGauss=# insert into employees values(17, 5, 'chenqi1'); +INSERT 0 1 +openGauss=# insert into employees values(18, 5, 'chenqi2'); +INSERT 0 1 +openGauss=# insert into employees values(19, 5, 'chenqi3'); +INSERT 0 1 +openGauss=# insert into employees values(20, 5, 'chenqi4'); +INSERT 0 1 +openGauss=# create function fn_salar (departmentid int) returns table (employee_id int, department_id int, last_name varchar) language sql as 'select employee_id, department_id, concat(last_name,last_name) as last_name2 from employees WHERE department_id = departmentid'; +CREATE FUNCTION + +-- 跨路径cross apply +openGauss=# SELECT d.department_name, v.employee_id, v.last_name +openGauss-# FROM departments d CROSS APPLY (SELECT * FROM employees e WHERE e.department_id = d.department_id) v +openGauss-# WHERE d.department_name IN ('Marketing', 'Operations', 'Public Relations', 'CEO', 'CFO') +openGauss-# ORDER BY d.department_name, v.employee_id; + department_name | employee_id | last_name +------------------+-------------+----------- + Marketing | 1 | zhangsan1 + Marketing | 2 | zhangsan2 + Marketing | 3 | zhangsan3 + Marketing | 4 | zhangsan4 + Operations | 9 | wangwu1 + Operations | 10 | wangwu2 + Operations | 11 | wangwu3 + Operations | 12 | wangwu4 + Public Relations | 5 | lisi1 + Public Relations | 6 | lisi2 + Public Relations | 7 | lisi3 + Public Relations | 8 | lisi4 + +-- cross apply function +openGauss=# SELECT * FROM employees AS e outer APPLY fn_Salar(e.department_id) AS f limit 5;; + employee_id | department_id | last_name | employee_id | department_id | last_name +-------------+---------------+-----------+-------------+---------------+-------------------- + 1 | 1 | zhangsan1 | 1 | 1 | zhangsan1zhangsan1 + 1 | 1 | zhangsan1 | 2 | 1 | zhangsan2zhangsan2 + 1 | 1 | zhangsan1 | 3 | 1 | zhangsan3zhangsan3 + 1 | 1 | zhangsan1 | 4 | 1 | zhangsan4zhangsan4 + 2 | 1 | zhangsan2 | 1 | 1 | zhangsan1zhangsan1 +(5 rows) + +-- 跨路径outer apply +openGauss=# SELECT d.department_name, v.employee_id, v.last_name +openGauss-# FROM departments d OUTER APPLY (SELECT * FROM employees e WHERE e.department_id = d.department_id) v +openGauss-# WHERE d.department_name IN ('Marketing', 'Operations', 'Public Relations', 'CEO', 'CFO') +openGauss-# ORDER BY d.department_name, v.employee_id; + department_name | employee_id | last_name +------------------+-------------+----------- + CEO | | + CFO | | + Marketing | 1 | zhangsan1 + Marketing | 2 | zhangsan2 + Marketing | 3 | zhangsan3 + Marketing | 4 | zhangsan4 + Operations | 9 | wangwu1 + Operations | 10 | wangwu2 + Operations | 11 | wangwu3 + Operations | 12 | wangwu4 + Public Relations | 5 | lisi1 + Public Relations | 6 | lisi2 + Public Relations | 7 | lisi3 + Public Relations | 8 | lisi4 +(14 rows) +```