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Merge pull request #2134 from zhang2014/fix/union_syntax

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ISSUES-2133 Support union query with subquery
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alexey-milovidov 2018-04-19 05:42:52 +03:00 committed by GitHub
commit b23db369f4
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6 changed files with 82 additions and 8 deletions
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31
dbms/src/Parsers/ParserSelectWithUnionQuery.cpp
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@ -1,7 +1,9 @@
#include <Parsers/ParserSelectQuery.h>
#include <Parsers/ExpressionListParsers.h>
#include <Parsers/ParserSelectWithUnionQuery.h>
#include <Parsers/ASTSelectWithUnionQuery.h>
#include <Parsers/ParserUnionQueryElement.h>
#include <Parsers/ASTExpressionList.h>
#include <Common/typeid_cast.h>
namespace DB
@ -11,17 +13,34 @@ bool ParserSelectWithUnionQuery::parseImpl(Pos & pos, ASTPtr & node, Expected &
{
ASTPtr list_node;
ParserList parser(std::make_unique<ParserSelectQuery>(), std::make_unique<ParserKeyword>("UNION ALL"), false);
ParserList parser(std::make_unique<ParserUnionQueryElement>(), std::make_unique<ParserKeyword>("UNION ALL"), false);
if (!parser.parse(pos, list_node, expected))
return false;
auto res = std::make_shared<ASTSelectWithUnionQuery>();
auto select_with_union_query = std::make_shared<ASTSelectWithUnionQuery>();
res->list_of_selects = std::move(list_node);
res->children.push_back(res->list_of_selects);
node = select_with_union_query;
select_with_union_query->list_of_selects = std::make_shared<ASTExpressionList>();
select_with_union_query->children.push_back(select_with_union_query->list_of_selects);
// flatten inner union query
for (auto & child : list_node->children)
getSelectsFromUnionListNode(child, select_with_union_query->list_of_selects->children);
node = res;
return true;
}
void ParserSelectWithUnionQuery::getSelectsFromUnionListNode(ASTPtr & ast_select, ASTs & selects)
{
if (ASTSelectWithUnionQuery * inner_union = typeid_cast<ASTSelectWithUnionQuery *>(ast_select.get()))
{
for (auto & child : inner_union->list_of_selects->children)
getSelectsFromUnionListNode(child, selects);
return;
}
selects.push_back(std::move(ast_select));
}
}

6
dbms/src/Parsers/ParserSelectWithUnionQuery.h
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@ -1,7 +1,6 @@
#pragma once
#include <Parsers/ParserQueryWithOutput.h>
#include <Parsers/IParserBase.h>
namespace DB
{
@ -12,6 +11,9 @@ class ParserSelectWithUnionQuery : public IParserBase
protected:
const char * getName() const override { return "SELECT query, possibly with UNION"; }
bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
private:
void getSelectsFromUnionListNode(ASTPtr & ast_select, ASTs & selects);
};
}

22
dbms/src/Parsers/ParserUnionQueryElement.cpp Normal file
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@ -0,0 +1,22 @@
#include <Parsers/ASTSubquery.h>
#include <Parsers/ExpressionElementParsers.h>
#include <Parsers/ParserSelectQuery.h>
#include <Parsers/ParserUnionQueryElement.h>
#include <Common/typeid_cast.h>
namespace DB
{
bool ParserUnionQueryElement::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
{
if (!ParserSubquery().parse(pos, node, expected) && !ParserSelectQuery().parse(pos, node, expected))
return false;
if (auto * ast_sub_query = typeid_cast<ASTSubquery *>(node.get()))
node = ast_sub_query->children.at(0);
return true;
}
}

17
dbms/src/Parsers/ParserUnionQueryElement.h Normal file
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@ -0,0 +1,17 @@
#pragma once
#include <Parsers/IParserBase.h>
namespace DB
{
class ParserUnionQueryElement : public IParserBase
{
protected:
const char * getName() const override { return "SELECT query, subquery, possibly with UNION"; }
bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
};
}

12
dbms/tests/queries/0_stateless/00612_union_query_with_subquery.reference Normal file
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@ -0,0 +1,12 @@
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2
dbms/tests/queries/0_stateless/00612_union_query_with_subquery.sql Normal file
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@ -0,0 +1,2 @@
SELECT * FROM ((SELECT * FROM system.numbers LIMIT 1) UNION ALL SELECT * FROM system.numbers LIMIT 2 UNION ALL (SELECT * FROM system.numbers LIMIT 3)) ORDER BY number;
SELECT * FROM (SELECT * FROM system.numbers LIMIT 1 UNION ALL (SELECT * FROM system.numbers LIMIT 2 UNION ALL (SELECT * FROM system.numbers LIMIT 3))) ORDER BY number;