gudusoft.gsqlparser.resolver

Class TStarColumnExpander

Object

gudusoft.gsqlparser.nodes.TParseTreeVisitor

gudusoft.gsqlparser.resolver.TStarColumnExpander

public class TStarColumnExpander
extends TParseTreeVisitor

TStarColumnExpander 负责解析和展开SQL查询中的星号列引用（*）。 工作流程： 1. 遍历所有SELECT语句 2. 对每个SELECT语句的结果列表进行处理 3. 识别并展开星号列引用： - 无限定符星号(*)：展开为FROM子句中所有表的所有列 - 限定符星号(table.*)：展开为指定表的所有列 4. 处理EXCEPT子句，从展开的列中移除指定列 Star column 解析后的列信息存储在 TObjectName 类的 attributeNodesDerivedFromFromClause 字段中： 处理示例： 1. SELECT * FROM employee -> SELECT employee.id, employee.name, employee.salary FROM employee 2. SELECT dept.* FROM department dept -> SELECT dept.id, dept.name, dept.location FROM department dept 3. SELECT emp.* EXCEPT (salary) FROM employee emp -> SELECT emp.id, emp.name FROM employee emp 关键组件： - sqlStack: 跟踪SELECT语句的嵌套层次 - scopeStack: 维护解析过程中的作用域 - globalScope: 存储全局SQL环境信息 与其他解析器的关系： - 在TRelationResolver之后执行 - 为TAttributeResolver准备展开后的列信息 - 依赖TDatabaseObjectResolver提供的表信息

Constructor Summary

Constructors

Constructor and Description
TStarColumnExpander(TStatementList sqls, gudusoft.gsqlparser.compiler.TContext scope, TSQLResolver resolver) Creates a new star column resolver instance.

Method Summary

Modifier and Type	Method and Description
void	postVisit(TSelectSqlStatement stmt) Processes star columns in SELECT statements after their FROM clause is processed.
void	preVisit(TSelectSqlStatement stmt) Tracks SELECT statements for proper scoping of star column resolution.
void	resolve() Main resolution method that processes all SQL statements.

Methods inherited from class gudusoft.gsqlparser.nodes.TParseTreeVisitor

postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, postVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit, preVisit

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TStarColumnExpander

public TStarColumnExpander(TStatementList sqls,
                           gudusoft.gsqlparser.compiler.TContext scope,
                           TSQLResolver resolver)

Creates a new star column resolver instance.

Parameters:

sqls - The SQL statements to analyze

scope - The global context containing SQL environment

Method Detail

resolve

public void resolve()

Main resolution method that processes all SQL statements. Iterates through statements and resolves star columns in each one.

preVisit

public void preVisit(TSelectSqlStatement stmt)

Tracks SELECT statements for proper scoping of star column resolution.

Overrides:

preVisit in class TParseTreeVisitor

Parameters:

stmt - The SELECT statement being processed

postVisit

public void postVisit(TSelectSqlStatement stmt)

Processes star columns in SELECT statements after their FROM clause is processed. Handles both unqualified (*) and qualified (table.*) star columns.

Overrides:

postVisit in class TParseTreeVisitor

Parameters:

stmt - The SELECT statement being processed