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.
42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
/*
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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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#include <LibSQL/AST/AST.h>
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#include <LibSQL/Database.h>
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#include <LibSQL/Meta.h>
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#include <LibSQL/Row.h>
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namespace SQL::AST {
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RefPtr<SQLResult> DescribeTable::execute(ExecutionContext& context) const
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{
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auto schema_name = m_qualified_table_name->schema_name();
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auto table_name = m_qualified_table_name->table_name();
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auto table_def_or_error = context.database->get_table(schema_name, table_name);
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auto table_def = table_def_or_error.release_value();
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if (!table_def) {
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if (schema_name.is_null() || schema_name.is_empty())
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schema_name = "default";
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return SQLResult::construct(SQLCommand::Describe, SQLErrorCode::TableDoesNotExist, String::formatted("{}.{}", schema_name, table_name));
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}
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auto describe_table_def = context.database->get_table("master", "internal_describe_table").value();
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NonnullRefPtr<TupleDescriptor> descriptor = describe_table_def->to_tuple_descriptor();
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context.result = SQLResult::construct();
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for (auto& column : table_def->columns()) {
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Tuple tuple(descriptor);
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tuple[0] = column.name();
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tuple[1] = SQLType_name(column.type());
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context.result->insert(tuple, Tuple {});
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}
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return context.result;
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}
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}
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