alamb commented on code in PR #3132: URL: https://github.com/apache/arrow-datafusion/pull/3132#discussion_r946044669
########## docs/source/user-guide/sql/subqueries.md: ########## @@ -0,0 +1,98 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Subqueries + +DataFusion supports `EXISTS`, `IN`, and Scalar Subqueries. Review Comment: ```suggestion DataFusion supports `EXISTS`, `NOT EXISTS`, `IN`, `NOT IN` and Scalar Subqueries. ``` ########## docs/source/user-guide/sql/subqueries.md: ########## @@ -0,0 +1,98 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Subqueries + +DataFusion supports `EXISTS`, `IN`, and Scalar Subqueries. + +The examples below are based on the following table. + +```sql +❯ select * from x; ++----------+----------+ +| column_1 | column_2 | ++----------+----------+ +| 1 | 2 | ++----------+----------+ +``` + +## EXISTS + +The `EXISTS` syntax can be used to find all rows in a relation where a correlated subquery produces one or more matches +for that row. Only correlated subqueries are supported. + +```sql +❯ select * from x y where exists (select * from x where x.column_1 = y.column_1); ++----------+----------+ +| column_1 | column_2 | ++----------+----------+ +| 1 | 2 | ++----------+----------+ +1 row in set. +``` + +## NOT EXISTS + +The `NOT EXISTS` syntax can be used to find all rows in a relation where a correlated subquery produces zero matches +for that row. Only correlated subqueries are supported. + +```sql +❯ select * from x y where not exists (select * from x where x.column_1 = y.column_1); +0 rows in set. +``` + +## IN + +The `IN` syntax can be used to find all rows in a relation where a given expression's value can be found in the +results of a correlated subquery. Only correlated subqueries are supported. Review Comment: ```suggestion results of a correlated subquery. ``` I think non correlated IN / NOT IN is also supported: ```sql ❯ select * from foo; +----+ | id | +----+ | 1 | | 3 | | 2 | | 10 | | 8 | +----+ 5 rows in set. Query took 0.002 seconds. ❯ select * from foo where id in (select id from foo); +----+ | id | +----+ | 1 | | 2 | | 3 | | 10 | | 8 | +----+ 5 rows in set. Query took 0.007 seconds. ❯ select * from foo where id not in (select id from foo); 0 rows in set. Query took 0.007 seconds. ``` ########## docs/source/user-guide/sql/subqueries.md: ########## @@ -0,0 +1,98 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Subqueries + +DataFusion supports `EXISTS`, `IN`, and Scalar Subqueries. + +The examples below are based on the following table. + +```sql +❯ select * from x; ++----------+----------+ +| column_1 | column_2 | ++----------+----------+ +| 1 | 2 | ++----------+----------+ +``` + +## EXISTS + +The `EXISTS` syntax can be used to find all rows in a relation where a correlated subquery produces one or more matches +for that row. Only correlated subqueries are supported. + +```sql +❯ select * from x y where exists (select * from x where x.column_1 = y.column_1); ++----------+----------+ +| column_1 | column_2 | ++----------+----------+ +| 1 | 2 | ++----------+----------+ +1 row in set. +``` + +## NOT EXISTS + +The `NOT EXISTS` syntax can be used to find all rows in a relation where a correlated subquery produces zero matches +for that row. Only correlated subqueries are supported. + +```sql +❯ select * from x y where not exists (select * from x where x.column_1 = y.column_1); +0 rows in set. +``` + +## IN + +The `IN` syntax can be used to find all rows in a relation where a given expression's value can be found in the +results of a correlated subquery. Only correlated subqueries are supported. + +```sql +❯ select * from x where column_1 in (select column_1 from x); ++----------+----------+ +| column_1 | column_2 | ++----------+----------+ +| 1 | 2 | ++----------+----------+ +1 row in set. +``` + +## NOT IN + +The `NOT IN` syntax can be used to find all rows in a relation where a given expression's value can not be found in the +results of a correlated subquery. Only correlated subqueries are supported. Review Comment: ```suggestion results of a correlated subquery. ``` -- This is an automated message from the Apache Git Service. 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