LibSQL: Parse (most of) SELECT statement

This doesn't yet parse join clauses, windowing functions, or compound
SELECT statements.

5 files changed, 555 insertions, 7 deletions

diff --git a/Userland/Libraries/LibSQL/AST.h b/Userland/Libraries/LibSQL/AST.h
index 677d94d874..fed6eaf0c0 100644
--- a/Userland/Libraries/LibSQL/AST.h
+++ b/Userland/Libraries/LibSQL/AST.h
@@ -154,6 +154,148 @@ private:
     Vector<ColumnClause> m_columns;
 };
 
+enum class ResultType {
+    All,
+    Table,
+    Expression,
+};
+
+class ResultColumn : public ASTNode {
+public:
+    ResultColumn() = default;
+
+    explicit ResultColumn(String table_name)
+        : m_type(ResultType::Table)
+        , m_table_name(move(table_name))
+    {
+    }
+
+    ResultColumn(NonnullRefPtr<Expression> expression, String column_alias)
+        : m_type(ResultType::Expression)
+        , m_expression(move(expression))
+        , m_column_alias(move(column_alias))
+    {
+    }
+
+    ResultType type() const { return m_type; }
+
+    bool select_from_table() const { return !m_table_name.is_null(); }
+    const String& table_name() const { return m_table_name; }
+
+    bool select_from_expression() const { return !m_expression.is_null(); }
+    const RefPtr<Expression>& expression() const { return m_expression; }
+    const String& column_alias() const { return m_column_alias; }
+
+private:
+    ResultType m_type { ResultType::All };
+
+    String m_table_name {};
+
+    RefPtr<Expression> m_expression {};
+    String m_column_alias {};
+};
+
+class GroupByClause : public ASTNode {
+public:
+    GroupByClause(NonnullRefPtrVector<Expression> group_by_list, RefPtr<Expression> having_clause)
+        : m_group_by_list(move(group_by_list))
+        , m_having_clause(move(having_clause))
+    {
+        VERIFY(!m_group_by_list.is_empty());
+    }
+
+    const NonnullRefPtrVector<Expression>& group_by_list() const { return m_group_by_list; }
+    const RefPtr<Expression>& having_clause() const { return m_having_clause; }
+
+private:
+    NonnullRefPtrVector<Expression> m_group_by_list;
+    RefPtr<Expression> m_having_clause;
+};
+
+class TableOrSubquery : public ASTNode {
+public:
+    TableOrSubquery() = default;
+
+    TableOrSubquery(String schema_name, String table_name, String table_alias)
+        : m_is_table(true)
+        , m_schema_name(move(schema_name))
+        , m_table_name(move(table_name))
+        , m_table_alias(move(table_alias))
+    {
+    }
+
+    explicit TableOrSubquery(NonnullRefPtrVector<TableOrSubquery> subqueries)
+        : m_is_subquery(!subqueries.is_empty())
+        , m_subqueries(move(subqueries))
+    {
+    }
+
+    bool is_table() const { return m_is_table; }
+    const String& schema_name() const { return m_schema_name; }
+    const String& table_name() const { return m_table_name; }
+    const String& table_alias() const { return m_table_alias; }
+
+    bool is_subquery() const { return m_is_subquery; }
+    const NonnullRefPtrVector<TableOrSubquery>& subqueries() const { return m_subqueries; }
+
+private:
+    bool m_is_table { false };
+    String m_schema_name {};
+    String m_table_name {};
+    String m_table_alias {};
+
+    bool m_is_subquery { false };
+    NonnullRefPtrVector<TableOrSubquery> m_subqueries {};
+};
+
+enum class Order {
+    Ascending,
+    Descending,
+};
+
+enum class Nulls {
+    First,
+    Last,
+};
+
+class OrderingTerm : public ASTNode {
+public:
+    OrderingTerm(NonnullRefPtr<Expression> expression, String collation_name, Order order, Nulls nulls)
+        : m_expression(move(expression))
+        , m_collation_name(move(collation_name))
+        , m_order(order)
+        , m_nulls(nulls)
+    {
+    }
+
+    const NonnullRefPtr<Expression>& expression() const { return m_expression; }
+    const String& collation_name() const { return m_collation_name; }
+    Order order() const { return m_order; }
+    Nulls nulls() const { return m_nulls; }
+
+private:
+    NonnullRefPtr<Expression> m_expression;
+    String m_collation_name;
+    Order m_order;
+    Nulls m_nulls;
+};
+
+class LimitClause : public ASTNode {
+public:
+    LimitClause(NonnullRefPtr<Expression> limit_expression, RefPtr<Expression> offset_expression)
+        : m_limit_expression(move(limit_expression))
+        , m_offset_expression(move(offset_expression))
+    {
+    }
+
+    const NonnullRefPtr<Expression>& limit_expression() const { return m_limit_expression; }
+    const RefPtr<Expression>& offset_expression() const { return m_offset_expression; }
+
+private:
+    NonnullRefPtr<Expression> m_limit_expression;
+    RefPtr<Expression> m_offset_expression;
+};
+
 //==================================================================================================
 // Expressions
 //==================================================================================================
@@ -570,4 +712,38 @@ private:
     RefPtr<ReturningClause> m_returning_clause;
 };
 
+class Select : public Statement {
+public:
+    Select(RefPtr<CommonTableExpressionList> common_table_expression_list, bool select_all, NonnullRefPtrVector<ResultColumn> result_column_list, NonnullRefPtrVector<TableOrSubquery> table_or_subquery_list, RefPtr<Expression> where_clause, RefPtr<GroupByClause> group_by_clause, NonnullRefPtrVector<OrderingTerm> ordering_term_list, RefPtr<LimitClause> limit_clause)
+        : m_common_table_expression_list(move(common_table_expression_list))
+        , m_select_all(move(select_all))
+        , m_result_column_list(move(result_column_list))
+        , m_table_or_subquery_list(move(table_or_subquery_list))
+        , m_where_clause(move(where_clause))
+        , m_group_by_clause(move(group_by_clause))
+        , m_ordering_term_list(move(ordering_term_list))
+        , m_limit_clause(move(limit_clause))
+    {
+    }
+
+    const RefPtr<CommonTableExpressionList>& common_table_expression_list() const { return m_common_table_expression_list; }
+    bool select_all() const { return m_select_all; }
+    const NonnullRefPtrVector<ResultColumn>& result_column_list() const { return m_result_column_list; }
+    const NonnullRefPtrVector<TableOrSubquery>& table_or_subquery_list() const { return m_table_or_subquery_list; }
+    const RefPtr<Expression>& where_clause() const { return m_where_clause; }
+    const RefPtr<GroupByClause>& group_by_clause() const { return m_group_by_clause; }
+    const NonnullRefPtrVector<OrderingTerm>& ordering_term_list() const { return m_ordering_term_list; }
+    const RefPtr<LimitClause>& limit_clause() const { return m_limit_clause; }
+
+private:
+    RefPtr<CommonTableExpressionList> m_common_table_expression_list;
+    bool m_select_all;
+    NonnullRefPtrVector<ResultColumn> m_result_column_list;
+    NonnullRefPtrVector<TableOrSubquery> m_table_or_subquery_list;
+    RefPtr<Expression> m_where_clause;
+    RefPtr<GroupByClause> m_group_by_clause;
+    NonnullRefPtrVector<OrderingTerm> m_ordering_term_list;
+    RefPtr<LimitClause> m_limit_clause;
+};
+
 }
diff --git a/Userland/Libraries/LibSQL/Forward.h b/Userland/Libraries/LibSQL/Forward.h
index d0949a5ddc..41104c72b5 100644
--- a/Userland/Libraries/LibSQL/Forward.h
+++ b/Userland/Libraries/LibSQL/Forward.h
@@ -25,24 +25,30 @@ class DropTable;
 class ErrorExpression;
 class ErrorStatement;
 class Expression;
+class GroupByClause;
 class InChainedExpression;
 class InTableExpression;
 class InvertibleNestedDoubleExpression;
 class InvertibleNestedExpression;
 class IsExpression;
 class Lexer;
+class LimitClause;
 class MatchExpression;
 class NestedDoubleExpression;
 class NestedExpression;
 class NullExpression;
 class NullLiteral;
 class NumericLiteral;
+class OrderingTerm;
 class Parser;
 class QualifiedTableName;
+class ResultColumn;
 class ReturningClause;
+class Select;
 class SignedNumber;
 class Statement;
 class StringLiteral;
+class TableOrSubquery;
 class Token;
 class TypeName;
 class UnaryOperatorExpression;
diff --git a/Userland/Libraries/LibSQL/Parser.cpp b/Userland/Libraries/LibSQL/Parser.cpp
index 3208ef9f78..79eadfb285 100644
--- a/Userland/Libraries/LibSQL/Parser.cpp
+++ b/Userland/Libraries/LibSQL/Parser.cpp
@@ -33,8 +33,10 @@ NonnullRefPtr<Statement> Parser::parse_statement()
         return parse_drop_table_statement();
     case TokenType::Delete:
         return parse_delete_statement({});
+    case TokenType::Select:
+        return parse_select_statement({});
     default:
-        expected("CREATE, DROP, or DELETE");
+        expected("CREATE, DROP, DELETE, or SELECT");
         return create_ast_node<ErrorStatement>();
     }
 }
@@ -44,8 +46,10 @@ NonnullRefPtr<Statement> Parser::parse_statement_with_expression_list(RefPtr<Com
     switch (m_parser_state.m_token.type()) {
     case TokenType::Delete:
         return parse_delete_statement(move(common_table_expression_list));
+    case TokenType::Select:
+        return parse_select_statement(move(common_table_expression_list));
     default:
-        expected("DELETE");
+        expected("DELETE or SELECT");
         return create_ast_node<ErrorStatement>();
     }
 }
@@ -148,6 +152,94 @@ NonnullRefPtr<Delete> Parser::parse_delete_statement(RefPtr<CommonTableExpressio
     return create_ast_node<Delete>(move(common_table_expression_list), move(qualified_table_name), move(where_clause), move(returning_clause));
 }
 
+NonnullRefPtr<Select> Parser::parse_select_statement(RefPtr<CommonTableExpressionList> common_table_expression_list)
+{
+    // https://sqlite.org/lang_select.html
+    consume(TokenType::Select);
+
+    bool select_all = !consume_if(TokenType::Distinct);
+    consume_if(TokenType::All); // ALL is the default, so ignore it if specified.
+
+    NonnullRefPtrVector<ResultColumn> result_column_list;
+    do {
+        result_column_list.append(parse_result_column());
+        if (!match(TokenType::Comma))
+            break;
+        consume(TokenType::Comma);
+    } while (!match(TokenType::Eof));
+
+    NonnullRefPtrVector<TableOrSubquery> table_or_subquery_list;
+    if (consume_if(TokenType::From)) {
+        // FIXME: Parse join-clause.
+
+        do {
+            table_or_subquery_list.append(parse_table_or_subquery());
+            if (!match(TokenType::Comma))
+                break;
+            consume(TokenType::Comma);
+        } while (!match(TokenType::Eof));
+    }
+
+    RefPtr<Expression> where_clause;
+    if (consume_if(TokenType::Where))
+        where_clause = parse_expression();
+
+    RefPtr<GroupByClause> group_by_clause;
+    if (consume_if(TokenType::Group)) {
+        consume(TokenType::By);
+
+        NonnullRefPtrVector<Expression> group_by_list;
+        do {
+            group_by_list.append(parse_expression());
+            if (!match(TokenType::Comma))
+                break;
+            consume(TokenType::Comma);
+        } while (!match(TokenType::Eof));
+
+        RefPtr<Expression> having_clause;
+        if (consume_if(TokenType::Having))
+            having_clause = parse_expression();
+
+        group_by_clause = create_ast_node<GroupByClause>(move(group_by_list), move(having_clause));
+    }
+
+    // FIXME: Parse 'WINDOW window-name AS window-defn'.
+    // FIXME: Parse 'compound-operator'.
+
+    NonnullRefPtrVector<OrderingTerm> ordering_term_list;
+    if (consume_if(TokenType::Order)) {
+        consume(TokenType::By);
+
+        do {
+            ordering_term_list.append(parse_ordering_term());
+            if (!match(TokenType::Comma))
+                break;
+            consume(TokenType::Comma);
+        } while (!match(TokenType::Eof));
+    }
+
+    RefPtr<LimitClause> limit_clause;
+    if (consume_if(TokenType::Limit)) {
+        auto limit_expression = parse_expression();
+
+        RefPtr<Expression> offset_expression;
+        if (consume_if(TokenType::Offset)) {
+            offset_expression = parse_expression();
+        } else {
+            // Note: The limit clause may instead be definied as "offset-expression, limit-expression", effectively reversing the
+            // order of the expressions. SQLite notes "this is counter-intuitive" and "to avoid confusion, programmers are strongly
+            // encouraged to ... avoid using a LIMIT clause with a comma-separated offset."
+            VERIFY(!consume_if(TokenType::Comma));
+        }
+
+        limit_clause = create_ast_node<LimitClause>(move(limit_expression), move(offset_expression));
+    }
+
+    consume(TokenType::SemiColon);
+
+    return create_ast_node<Select>(move(common_table_expression_list), select_all, move(result_column_list), move(table_or_subquery_list), move(where_clause), move(group_by_clause), move(ordering_term_list), move(limit_clause));
+}
+
 NonnullRefPtr<CommonTableExpressionList> Parser::parse_common_table_expression_list()
 {
     consume(TokenType::With);
@@ -297,17 +389,22 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_literal_value_expression()
     return {};
 }
 
-Optional<NonnullRefPtr<Expression>> Parser::parse_column_name_expression()
+Optional<NonnullRefPtr<Expression>> Parser::parse_column_name_expression(String with_parsed_identifier, bool with_parsed_period)
 {
-    if (!match(TokenType::Identifier))
+    if (with_parsed_identifier.is_null() && !match(TokenType::Identifier))
         return {};
 
-    String first_identifier = consume(TokenType::Identifier).value();
+    String first_identifier;
+    if (with_parsed_identifier.is_null())
+        first_identifier = consume(TokenType::Identifier).value();
+    else
+        first_identifier = move(with_parsed_identifier);
+
     String schema_name;
     String table_name;
     String column_name;
 
-    if (consume_if(TokenType::Period)) {
+    if (with_parsed_period || consume_if(TokenType::Period)) {
         String second_identifier = consume(TokenType::Identifier).value();
 
         if (consume_if(TokenType::Period)) {
@@ -741,6 +838,107 @@ NonnullRefPtr<ReturningClause> Parser::parse_returning_clause()
     return create_ast_node<ReturningClause>(move(columns));
 }
 
+NonnullRefPtr<ResultColumn> Parser::parse_result_column()
+{
+    // https://sqlite.org/syntax/result-column.html
+    if (consume_if(TokenType::Asterisk))
+        return create_ast_node<ResultColumn>();
+
+    // If we match an identifier now, we don't know whether it is a table-name of the form "table-name.*", or if it is the start of a
+    // column-name-expression, until we try to parse the asterisk. So if we consume an indentifier and a period, but don't find an
+    // asterisk, hold onto that information to form a column-name-expression later.
+    String table_name;
+    bool parsed_period = false;
+
+    if (match(TokenType::Identifier)) {
+        table_name = consume().value();
+        parsed_period = consume_if(TokenType::Period);
+        if (parsed_period && consume_if(TokenType::Asterisk))
+            return create_ast_node<ResultColumn>(move(table_name));
+    }
+
+    auto expression = table_name.is_null()
+        ? parse_expression()
+        : static_cast<NonnullRefPtr<Expression>>(*parse_column_name_expression(move(table_name), parsed_period));
+    consume_if(TokenType::As); // 'AS' is optional.
+
+    String column_alias;
+    if (match(TokenType::Identifier))
+        column_alias = consume().value();
+
+    return create_ast_node<ResultColumn>(move(expression), move(column_alias));
+}
+
+NonnullRefPtr<TableOrSubquery> Parser::parse_table_or_subquery()
+{
+    // https://sqlite.org/syntax/table-or-subquery.html
+    if (match(TokenType::Identifier)) {
+        String schema_or_table_name = consume().value();
+        String schema_name;
+        String table_name;
+
+        if (consume_if(TokenType::Period)) {
+            schema_name = move(schema_or_table_name);
+            table_name = consume(TokenType::Identifier).value();
+        } else {
+            table_name = move(schema_or_table_name);
+        }
+
+        consume_if(TokenType::As); // 'AS' is optional.
+
+        String table_alias;
+        if (match(TokenType::Identifier))
+            table_alias = consume().value();
+
+        return create_ast_node<TableOrSubquery>(move(schema_name), move(table_name), move(table_alias));
+    }
+
+    consume(TokenType::ParenOpen);
+    // FIXME: Parse join-clause.
+
+    NonnullRefPtrVector<TableOrSubquery> subqueries;
+    while (!has_errors() && !match(TokenType::Eof)) {
+        subqueries.append(parse_table_or_subquery());
+        if (!match(TokenType::Comma))
+            break;
+        consume(TokenType::Comma);
+    }
+
+    consume(TokenType::ParenClose);
+
+    return create_ast_node<TableOrSubquery>(move(subqueries));
+}
+
+NonnullRefPtr<OrderingTerm> Parser::parse_ordering_term()
+{
+    // https://sqlite.org/syntax/ordering-term.html
+    auto expression = parse_expression();
+
+    String collation_name;
+    if (is<CollateExpression>(*expression)) {
+        const auto& collate = static_cast<const CollateExpression&>(*expression);
+        collation_name = collate.collation_name();
+        expression = collate.expression();
+    } else if (consume_if(TokenType::Collate)) {
+        collation_name = consume(TokenType::Identifier).value();
+    }
+
+    Order order = consume_if(TokenType::Desc) ? Order::Descending : Order::Ascending;
+    consume_if(TokenType::Asc); // ASC is the default, so ignore it if specified.
+
+    Nulls nulls = order == Order::Ascending ? Nulls::First : Nulls::Last;
+    if (consume_if(TokenType::Nulls)) {
+        if (consume_if(TokenType::First))
+            nulls = Nulls::First;
+        else if (consume_if(TokenType::Last))
+            nulls = Nulls::Last;
+        else
+            expected("FIRST or LAST");
+    }
+
+    return create_ast_node<OrderingTerm>(move(expression), move(collation_name), order, nulls);
+}
+
 Token Parser::consume()
 {
     auto old_token = m_parser_state.m_token;
diff --git a/Userland/Libraries/LibSQL/Parser.h b/Userland/Libraries/LibSQL/Parser.h
index 1a4796171a..8e0419371c 100644
--- a/Userland/Libraries/LibSQL/Parser.h
+++ b/Userland/Libraries/LibSQL/Parser.h
@@ -55,13 +55,14 @@ private:
     NonnullRefPtr<CreateTable> parse_create_table_statement();
     NonnullRefPtr<DropTable> parse_drop_table_statement();
     NonnullRefPtr<Delete> parse_delete_statement(RefPtr<CommonTableExpressionList>);
+    NonnullRefPtr<Select> parse_select_statement(RefPtr<CommonTableExpressionList>);
     NonnullRefPtr<CommonTableExpressionList> parse_common_table_expression_list();
 
     NonnullRefPtr<Expression> parse_primary_expression();
     NonnullRefPtr<Expression> parse_secondary_expression(NonnullRefPtr<Expression> primary);
     bool match_secondary_expression() const;
     Optional<NonnullRefPtr<Expression>> parse_literal_value_expression();
-    Optional<NonnullRefPtr<Expression>> parse_column_name_expression();
+    Optional<NonnullRefPtr<Expression>> parse_column_name_expression(String with_parsed_identifier = {}, bool with_parsed_period = false);
     Optional<NonnullRefPtr<Expression>> parse_unary_operator_expression();
     Optional<NonnullRefPtr<Expression>> parse_binary_operator_expression(NonnullRefPtr<Expression> lhs);
     Optional<NonnullRefPtr<Expression>> parse_chained_expression();
@@ -80,6 +81,9 @@ private:
     NonnullRefPtr<CommonTableExpression> parse_common_table_expression();
     NonnullRefPtr<QualifiedTableName> parse_qualified_table_name();
     NonnullRefPtr<ReturningClause> parse_returning_clause();
+    NonnullRefPtr<ResultColumn> parse_result_column();
+    NonnullRefPtr<TableOrSubquery> parse_table_or_subquery();
+    NonnullRefPtr<OrderingTerm> parse_ordering_term();
 
     Token consume();
     Token consume(TokenType type);
diff --git a/Userland/Libraries/LibSQL/Tests/TestSqlStatementParser.cpp b/Userland/Libraries/LibSQL/Tests/TestSqlStatementParser.cpp
index 5dc40b8311..c4c0fe36cb 100644
--- a/Userland/Libraries/LibSQL/Tests/TestSqlStatementParser.cpp
+++ b/Userland/Libraries/LibSQL/Tests/TestSqlStatementParser.cpp
@@ -234,4 +234,168 @@ TEST_CASE(delete_)
     validate("WITH RECURSIVE table AS () DELETE FROM table;", { true, { { "table", {} } } }, {}, "table", {}, false, false, {});
 }
 
+TEST_CASE(select)
+{
+    EXPECT(parse("SELECT").is_error());
+    EXPECT(parse("SELECT;").is_error());
+    EXPECT(parse("SELECT DISTINCT;").is_error());
+    EXPECT(parse("SELECT ALL;").is_error());
+    EXPECT(parse("SELECT *").is_error());
+    EXPECT(parse("SELECT * FROM;").is_error());
+    EXPECT(parse("SELECT table. FROM table;").is_error());
+    EXPECT(parse("SELECT * FROM (").is_error());
+    EXPECT(parse("SELECT * FROM ()").is_error());
+    EXPECT(parse("SELECT * FROM ();").is_error());
+    EXPECT(parse("SELECT * FROM (table1)").is_error());
+    EXPECT(parse("SELECT * FROM (table1, )").is_error());
+    EXPECT(parse("SELECT * FROM (table1, table2)").is_error());
+    EXPECT(parse("SELECT * FROM table").is_error());
+    EXPECT(parse("SELECT * FROM table WHERE;").is_error());
+    EXPECT(parse("SELECT * FROM table WHERE 1 ==1").is_error());
+    EXPECT(parse("SELECT * FROM table GROUP;").is_error());
+    EXPECT(parse("SELECT * FROM table GROUP BY;").is_error());
+    EXPECT(parse("SELECT * FROM table GROUP BY column").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER:").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER BY column").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER BY column COLLATE:").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER BY column COLLATE collation").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER BY column NULLS;").is_error());
+    EXPECT(parse("SELECT * FROM table ORDER BY column NULLS SECOND;").is_error());
+    EXPECT(parse("SELECT * FROM table LIMIT;").is_error());
+    EXPECT(parse("SELECT * FROM table LIMIT 12").is_error());
+    EXPECT(parse("SELECT * FROM table LIMIT 12 OFFSET;").is_error());
+    EXPECT(parse("SELECT * FROM table LIMIT 12 OFFSET 15").is_error());
+
+    struct Type {
+        SQL::ResultType type;
+        StringView table_name_or_column_alias {};
+    };
+
+    struct From {
+        StringView schema_name;
+        StringView table_name;
+        StringView table_alias;
+    };
+
+    struct Ordering {
+        String collation_name;
+        SQL::Order order;
+        SQL::Nulls nulls;
+    };
+
+    auto validate = [](StringView sql, Vector<Type> expected_columns, Vector<From> expected_from_list, bool expect_where_clause, size_t expected_group_by_size, bool expect_having_clause, Vector<Ordering> expected_ordering, bool expect_limit_clause, bool expect_offset_clause) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::Select>(*statement));
+
+        const auto& select = static_cast<const SQL::Select&>(*statement);
+
+        const auto& result_column_list = select.result_column_list();
+        EXPECT_EQ(result_column_list.size(), expected_columns.size());
+        for (size_t i = 0; i < result_column_list.size(); ++i) {
+            const auto& result_column = result_column_list[i];
+            const auto& expected_column = expected_columns[i];
+            EXPECT_EQ(result_column.type(), expected_column.type);
+
+            switch (result_column.type()) {
+            case SQL::ResultType::All:
+                EXPECT(expected_column.table_name_or_column_alias.is_null());
+                break;
+            case SQL::ResultType::Table:
+                EXPECT_EQ(result_column.table_name(), expected_column.table_name_or_column_alias);
+                break;
+            case SQL::ResultType::Expression:
+                EXPECT_EQ(result_column.column_alias(), expected_column.table_name_or_column_alias);
+                break;
+            }
+        }
+
+        const auto& table_or_subquery_list = select.table_or_subquery_list();
+        EXPECT_EQ(table_or_subquery_list.size(), expected_from_list.size());
+        for (size_t i = 0; i < table_or_subquery_list.size(); ++i) {
+            const auto& result_from = table_or_subquery_list[i];
+            const auto& expected_from = expected_from_list[i];
+            EXPECT_EQ(result_from.schema_name(), expected_from.schema_name);
+            EXPECT_EQ(result_from.table_name(), expected_from.table_name);
+            EXPECT_EQ(result_from.table_alias(), expected_from.table_alias);
+        }
+
+        const auto& where_clause = select.where_clause();
+        EXPECT_EQ(where_clause.is_null(), !expect_where_clause);
+        if (where_clause)
+            EXPECT(!is<SQL::ErrorExpression>(*where_clause));
+
+        const auto& group_by_clause = select.group_by_clause();
+        EXPECT_EQ(group_by_clause.is_null(), (expected_group_by_size == 0));
+        if (group_by_clause) {
+            const auto& group_by_list = group_by_clause->group_by_list();
+            EXPECT_EQ(group_by_list.size(), expected_group_by_size);
+            for (size_t i = 0; i < group_by_list.size(); ++i)
+                EXPECT(!is<SQL::ErrorExpression>(group_by_list[i]));
+
+            const auto& having_clause = group_by_clause->having_clause();
+            EXPECT_EQ(having_clause.is_null(), !expect_having_clause);
+            if (having_clause)
+                EXPECT(!is<SQL::ErrorExpression>(*having_clause));
+        }
+
+        const auto& ordering_term_list = select.ordering_term_list();
+        EXPECT_EQ(ordering_term_list.size(), expected_ordering.size());
+        for (size_t i = 0; i < ordering_term_list.size(); ++i) {
+            const auto& result_order = ordering_term_list[i];
+            const auto& expected_order = expected_ordering[i];
+            EXPECT(!is<SQL::ErrorExpression>(*result_order.expression()));
+            EXPECT_EQ(result_order.collation_name(), expected_order.collation_name);
+            EXPECT_EQ(result_order.order(), expected_order.order);
+            EXPECT_EQ(result_order.nulls(), expected_order.nulls);
+        }
+
+        const auto& limit_clause = select.limit_clause();
+        EXPECT_EQ(limit_clause.is_null(), !expect_limit_clause);
+        if (limit_clause) {
+            const auto& limit_expression = limit_clause->limit_expression();
+            EXPECT(!is<SQL::ErrorExpression>(*limit_expression));
+
+            const auto& offset_expression = limit_clause->offset_expression();
+            EXPECT_EQ(offset_expression.is_null(), !expect_offset_clause);
+            if (offset_expression)
+                EXPECT(!is<SQL::ErrorExpression>(*offset_expression));
+        }
+    };
+
+    Vector<Type> all { { SQL::ResultType::All } };
+    Vector<From> from { { {}, "table", {} } };
+
+    validate("SELECT * FROM table;", { { SQL::ResultType::All } }, from, false, 0, false, {}, false, false);
+    validate("SELECT table.* FROM table;", { { SQL::ResultType::Table, "table" } }, from, false, 0, false, {}, false, false);
+    validate("SELECT column AS alias FROM table;", { { SQL::ResultType::Expression, "alias" } }, from, false, 0, false, {}, false, false);
+    validate("SELECT table.column AS alias FROM table;", { { SQL::ResultType::Expression, "alias" } }, from, false, 0, false, {}, false, false);
+    validate("SELECT schema.table.column AS alias FROM table;", { { SQL::ResultType::Expression, "alias" } }, from, false, 0, false, {}, false, false);
+    validate("SELECT column AS alias, *, table.* FROM table;", { { SQL::ResultType::Expression, "alias" }, { SQL::ResultType::All }, { SQL::ResultType::Table, "table" } }, from, false, 0, false, {}, false, false);
+
+    validate("SELECT * FROM table;", all, { { {}, "table", {} } }, false, 0, false, {}, false, false);
+    validate("SELECT * FROM schema.table;", all, { { "schema", "table", {} } }, false, 0, false, {}, false, false);
+    validate("SELECT * FROM schema.table AS alias;", all, { { "schema", "table", "alias" } }, false, 0, false, {}, false, false);
+    validate("SELECT * FROM schema.table AS alias, table2, table3 AS table4;", all, { { "schema", "table", "alias" }, { {}, "table2", {} }, { {}, "table3", "table4" } }, false, 0, false, {}, false, false);
+
+    validate("SELECT * FROM table WHERE column IS NOT NULL;", all, from, true, 0, false, {}, false, false);
+
+    validate("SELECT * FROM table GROUP BY column;", all, from, false, 1, false, {}, false, false);
+    validate("SELECT * FROM table GROUP BY column1, column2, column3;", all, from, false, 3, false, {}, false, false);
+    validate("SELECT * FROM table GROUP BY column HAVING 'abc';", all, from, false, 1, true, {}, false, false);
+
+    validate("SELECT * FROM table ORDER BY column;", all, from, false, 0, false, { { {}, SQL::Order::Ascending, SQL::Nulls::First } }, false, false);
+    validate("SELECT * FROM table ORDER BY column COLLATE collation;", all, from, false, 0, false, { { "collation", SQL::Order::Ascending, SQL::Nulls::First } }, false, false);
+    validate("SELECT * FROM table ORDER BY column ASC;", all, from, false, 0, false, { { {}, SQL::Order::Ascending, SQL::Nulls::First } }, false, false);
+    validate("SELECT * FROM table ORDER BY column DESC;", all, from, false, 0, false, { { {}, SQL::Order::Descending, SQL::Nulls::Last } }, false, false);
+    validate("SELECT * FROM table ORDER BY column ASC NULLS LAST;", all, from, false, 0, false, { { {}, SQL::Order::Ascending, SQL::Nulls::Last } }, false, false);
+    validate("SELECT * FROM table ORDER BY column DESC NULLS FIRST;", all, from, false, 0, false, { { {}, SQL::Order::Descending, SQL::Nulls::First } }, false, false);
+    validate("SELECT * FROM table ORDER BY column1, column2 DESC, column3 NULLS LAST;", all, from, false, 0, false, { { {}, SQL::Order::Ascending, SQL::Nulls::First }, { {}, SQL::Order::Descending, SQL::Nulls::Last }, { {}, SQL::Order::Ascending, SQL::Nulls::Last } }, false, false);
+
+    validate("SELECT * FROM table LIMIT 15;", all, from, false, 0, false, {}, true, false);
+    validate("SELECT * FROM table LIMIT 15 OFFSET 16;", all, from, false, 0, false, {}, true, true);
+}
+
 TEST_MAIN(SqlStatementParser)