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71 lines
1.5 KiB
C++
71 lines
1.5 KiB
C++
#pragma once
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#include <DB/Storages/IStorage.h>
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#include <DB/Parsers/TablePropertiesQueriesASTs.h>
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#include <DB/Interpreters/Context.h>
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#include <DB/Interpreters/IInterpreter.h>
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#include <DB/DataStreams/OneBlockInputStream.h>
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#include <DB/DataStreams/BlockIO.h>
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#include <DB/DataStreams/copyData.h>
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#include <DB/DataTypes/DataTypesNumberFixed.h>
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namespace DB
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{
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/** Проверить, существует ли таблица. Вернуть одну строку с одним столбцом result типа UInt8 со значением 0 или 1.
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*/
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class InterpreterExistsQuery : public IInterpreter
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{
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public:
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InterpreterExistsQuery(ASTPtr query_ptr_, Context & context_)
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: query_ptr(query_ptr_), context(context_) {}
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BlockIO execute() override
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{
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BlockIO res;
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res.in = executeImpl();
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res.in_sample = getSampleBlock();
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return res;
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}
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private:
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ASTPtr query_ptr;
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Context context;
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Block getSampleBlock()
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{
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ColumnWithTypeAndName col;
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col.name = "result";
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col.type = std::make_shared<DataTypeUInt8>();
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col.column = col.type->createColumn();
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Block block;
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block.insert(col);
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return block;
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}
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BlockInputStreamPtr executeImpl()
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{
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const ASTExistsQuery & ast = typeid_cast<const ASTExistsQuery &>(*query_ptr);
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bool res = context.isTableExist(ast.database, ast.table);
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ColumnWithTypeAndName col;
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col.name = "result";
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col.type = std::make_shared<DataTypeUInt8>();
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col.column = std::make_shared<ColumnConstUInt8>(1, res);
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Block block;
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block.insert(col);
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return new OneBlockInputStream(block);
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}
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};
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}
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