Alias (H2 Database Engine 2.0.0 API)

java.lang.Object
- org.h2.expression.Expression
- - org.h2.expression.Alias

所有已实现的接口:

HasSQL, Typed
```
public final class Alias
extends Expression
```
A column alias as in SELECT 'Hello' AS NAME ...

字段概要
- 从类继承的字段 org.h2.expression.Expression
  AUTO_PARENTHESES, MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL, WITH_PARENTHESES, WITHOUT_PARENTHESES
- 从接口继承的字段 org.h2.util.HasSQL
  ADD_PLAN_INFORMATION, DEFAULT_SQL_FLAGS, NO_CASTS, QUOTE_ONLY_WHEN_REQUIRED, REPLACE_LOBS_FOR_TRACE, TRACE_SQL_FLAGS

构造器概要

构造器
构造器和说明

Alias(Expression expression, String alias, boolean aliasColumnName)

构造器
构造器和说明
`Alias(Expression expression, String alias, boolean aliasColumnName)`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`String`	`getAlias(SessionLocal session, int columnIndex)` Get the alias name of a column or SQL expression if it is not an aliased expression.
`String`	`getColumnName(SessionLocal session, int columnIndex)` Get the column name or alias name of this expression.
`String`	`getColumnNameForView(SessionLocal session, int columnIndex)` Get the column name of this expression for a view.
`int`	`getCost()` Estimate the cost to process the expression.
`Expression`	`getNonAliasExpression()` Returns the main expression, skipping aliases.
`int`	`getNullable()` Check whether this expression is a column and can store NULL.
`String`	`getSchemaName()` Get the schema name, or null
`String`	`getTableName()` Get the table name, or null
`TypeInfo`	`getType()` Returns the data type.
`StringBuilder`	`getUnenclosedSQL(StringBuilder builder, int sqlFlags)` Get the SQL statement of this expression.
`Value`	`getValue(SessionLocal session)` Return the resulting value for the current row.
`boolean`	`isEverything(ExpressionVisitor visitor)` Check if this expression and all sub-expressions can fulfill a criteria.
`boolean`	`isIdentity()` Check if this is an identity column.
`void`	`mapColumns(ColumnResolver resolver, int level, int state)` Map the columns of the resolver to expression columns.
`Expression`	`optimize(SessionLocal session)` Try to optimize the expression.
`void`	`setEvaluatable(TableFilter tableFilter, boolean b)` Tell the expression columns whether the table filter can return values now.
`void`	`updateAggregate(SessionLocal session, int stage)` Update an aggregate value.

从类继承的方法 org.h2.expression.Expression
addFilterConditions, createIndexConditions, getBooleanValue, getEnclosedSQL, getNotIfPossible, getSQL, getSQL, getSQL, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getWhenSQL, getWhenValue, isConstant, isNullConstant, isValueSet, isWhenConditionOperand, needParentheses, optimizeCondition, toString, writeExpressions, writeExpressions

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

从接口继承的方法 org.h2.util.HasSQL
getTraceSQL

- 构造器详细资料
  - Alias
```
public Alias(Expression expression,
             String alias,
             boolean aliasColumnName)
```
- 方法详细资料
  - getNonAliasExpression
```
public Expression getNonAliasExpression()
```
    从类复制的说明: Expression
    
    Returns the main expression, skipping aliases.
    
    覆盖:
    
    getNonAliasExpression 在类中 Expression
    
    返回:
    
    the expression
  - getValue
```
public Value getValue(SessionLocal session)
```
    从类复制的说明: Expression
    
    Return the resulting value for the current row.
    
    指定者:
    
    getValue 在类中 Expression
    
    参数:
    
    session - the session
    
    返回:
    
    the result
  - getType
```
public TypeInfo getType()
```
    从类复制的说明: Expression
    
    Returns the data type. The data type may be unknown before the optimization phase.
    
    指定者:
    
    getType 在接口中 Typed
    
    指定者:
    
    getType 在类中 Expression
    
    返回:
    
    the data type
  - mapColumns
```
public void mapColumns(ColumnResolver resolver,
                       int level,
                       int state)
```
    从类复制的说明: Expression
    
    Map the columns of the resolver to expression columns.
    
    指定者:
    
    mapColumns 在类中 Expression
    
    参数:
    
    resolver - the column resolver
    
    level - the subquery nesting level
    
    state - current state for nesting checks, initial value is Expression.MAP_INITIAL
  - optimize
```
public Expression optimize(SessionLocal session)
```
    从类复制的说明: Expression
    
    Try to optimize the expression.
    
    指定者:
    
    optimize 在类中 Expression
    
    参数:
    
    session - the session
    
    返回:
    
    the optimized expression
  - setEvaluatable
```
public void setEvaluatable(TableFilter tableFilter,
                           boolean b)
```
    从类复制的说明: Expression
    
    Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.
    
    指定者:
    
    setEvaluatable 在类中 Expression
    
    参数:
    
    tableFilter - the table filter
    
    b - true if the table filter can return value
  - isIdentity
```
public boolean isIdentity()
```
    从类复制的说明: Expression
    
    Check if this is an identity column.
    
    覆盖:
    
    isIdentity 在类中 Expression
    
    返回:
    
    true if it is an identity column
  - getUnenclosedSQL
```
public StringBuilder getUnenclosedSQL(StringBuilder builder,
                                      int sqlFlags)
```
    从类复制的说明: Expression
    
    Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are never appended.
    
    指定者:
    
    getUnenclosedSQL 在类中 Expression
    
    参数:
    
    builder - string builder
    
    sqlFlags - formatting flags
    
    返回:
    
    the specified string builder
  - updateAggregate
```
public void updateAggregate(SessionLocal session,
                            int stage)
```
    从类复制的说明: Expression
    
    Update an aggregate value. This method is called at statement execution time. It is usually called once for each row, but if the expression is used multiple times (for example in the column list, and as part of the HAVING expression) it is called multiple times - the row counter needs to be used to make sure the internal state is only updated once.
    
    指定者:
    
    updateAggregate 在类中 Expression
    
    参数:
    
    session - the session
    
    stage - select stage
  - getAlias
```
public String getAlias(SessionLocal session,
                       int columnIndex)
```
    从类复制的说明: Expression
    
    Get the alias name of a column or SQL expression if it is not an aliased expression.
    
    覆盖:
    
    getAlias 在类中 Expression
    
    参数:
    
    session - the session
    
    columnIndex - 0-based column index
    
    返回:
    
    the alias name
  - getColumnNameForView
```
public String getColumnNameForView(SessionLocal session,
                                   int columnIndex)
```
    从类复制的说明: Expression
    
    Get the column name of this expression for a view.
    
    覆盖:
    
    getColumnNameForView 在类中 Expression
    
    参数:
    
    session - the session
    
    columnIndex - 0-based column index
    
    返回:
    
    the column name for a view
  - getNullable
```
public int getNullable()
```
    从类复制的说明: Expression
    
    Check whether this expression is a column and can store NULL.
    
    覆盖:
    
    getNullable 在类中 Expression
    
    返回:
    
    whether NULL is allowed
  - isEverything
```
public boolean isEverything(ExpressionVisitor visitor)
```
    从类复制的说明: Expression
    
    Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.
    
    指定者:
    
    isEverything 在类中 Expression
    
    参数:
    
    visitor - the visitor
    
    返回:
    
    if the criteria can be fulfilled
  - getCost
```
public int getCost()
```
    从类复制的说明: Expression
    
    Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.
    
    指定者:
    
    getCost 在类中 Expression
    
    返回:
    
    the estimated cost
  - getSchemaName
```
public String getSchemaName()
```
    从类复制的说明: Expression
    
    Get the schema name, or null
    
    覆盖:
    
    getSchemaName 在类中 Expression
    
    返回:
    
    the schema name
  - getTableName
```
public String getTableName()
```
    从类复制的说明: Expression
    
    Get the table name, or null
    
    覆盖:
    
    getTableName 在类中 Expression
    
    返回:
    
    the table name
  - getColumnName
```
public String getColumnName(SessionLocal session,
                            int columnIndex)
```
    从类复制的说明: Expression
    
    Get the column name or alias name of this expression.
    
    覆盖:
    
    getColumnName 在类中 Expression
    
    参数:
    
    session - the session
    
    columnIndex - 0-based column index
    
    返回:
    
    the column name

类 Alias

字段概要

从类继承的字段 org.h2.expression.Expression

从接口继承的字段 org.h2.util.HasSQL

构造器概要

方法概要

从类继承的方法 org.h2.expression.Expression

从类继承的方法 java.lang.Object

从接口继承的方法 org.h2.util.HasSQL

构造器详细资料

Alias

方法详细资料

getNonAliasExpression

getValue

getType

mapColumns

optimize

setEvaluatable

isIdentity

getUnenclosedSQL

updateAggregate

getAlias

getColumnNameForView

getNullable

isEverything

getCost

getSchemaName

getTableName

getColumnName