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		f6233913ad
		
	
	
	
	
		
			
			This statement (for now) outputs the name and types of the different attributes in a table. It's not standard SQL but all DBMSs that I know of implement a sort of statement for such functionality. Since the output of DESCRIBE TABLE is just a relation, an internal schema, `master` was created and a table definition for DESCRIBE into it. The table definition and the master schema are not accessible by the user.
		
			
				
	
	
		
			61 lines
		
	
	
	
		
			1.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			61 lines
		
	
	
	
		
			1.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
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|  * Copyright (c) 2021, Mahmoud Mandour <ma.mandourr@gmail.com>
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|  *
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|  * SPDX-License-Identifier: BSD-2-Clause
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|  */
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| 
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| #pragma once
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| 
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| #include <AK/RefPtr.h>
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| #include <AK/String.h>
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| #include <LibCore/Object.h>
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| #include <LibSQL/Forward.h>
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| #include <LibSQL/Heap.h>
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| #include <LibSQL/Meta.h>
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| 
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| namespace SQL {
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| 
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| /**
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|  * A Database object logically connects a Heap with the SQL data we want
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|  * to store in it. It has BTree pointers for B-Trees holding the definitions
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|  * of tables, columns, indexes, and other SQL objects.
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|  */
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| class Database : public Core::Object {
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|     C_OBJECT(Database);
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| 
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| public:
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|     ~Database() override;
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| 
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|     ErrorOr<void> open();
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|     bool is_open() const { return m_open; }
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|     ErrorOr<void> commit();
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| 
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|     ErrorOr<void> add_schema(SchemaDef const&);
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|     static Key get_schema_key(String const&);
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|     ErrorOr<RefPtr<SchemaDef>> get_schema(String const&);
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| 
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|     ErrorOr<void> add_table(TableDef& table);
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|     static Key get_table_key(String const&, String const&);
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|     ErrorOr<RefPtr<TableDef>> get_table(String const&, String const&);
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| 
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|     ErrorOr<Vector<Row>> select_all(TableDef const&);
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|     ErrorOr<Vector<Row>> match(TableDef const&, Key const&);
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|     ErrorOr<void> insert(Row&);
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|     ErrorOr<void> update(Row&);
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| 
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| private:
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|     explicit Database(String);
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| 
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|     bool m_open { false };
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|     NonnullRefPtr<Heap> m_heap;
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|     Serializer m_serializer;
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|     RefPtr<BTree> m_schemas;
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|     RefPtr<BTree> m_tables;
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|     RefPtr<BTree> m_table_columns;
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| 
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|     HashMap<u32, RefPtr<SchemaDef>> m_schema_cache;
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|     HashMap<u32, RefPtr<TableDef>> m_table_cache;
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| };
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| 
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| }
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