Command (H2 Database Engine wt-1.0.1 API)

java.lang.Object
- org.h2.command.Command

所有已实现的接口:

CommandInterface

直接已知子类:

CommandContainer
```
public abstract class Command
extends Object
implements CommandInterface
```
Represents a SQL statement. This object is only used on the server side.

字段概要

字段
限定符和类型字段和说明

protected Session session
The session.

protected long startTimeNanos
The last start time.
- 从接口继承的字段 org.h2.command.CommandInterface
  ALTER_INDEX_RENAME, ALTER_SCHEMA_RENAME, ALTER_SEQUENCE, ALTER_TABLE_ADD_COLUMN, ALTER_TABLE_ADD_CONSTRAINT_CHECK, ALTER_TABLE_ADD_CONSTRAINT_PRIMARY_KEY, ALTER_TABLE_ADD_CONSTRAINT_REFERENTIAL, ALTER_TABLE_ADD_CONSTRAINT_UNIQUE, ALTER_TABLE_ALTER_COLUMN_CHANGE_TYPE, ALTER_TABLE_ALTER_COLUMN_DEFAULT, ALTER_TABLE_ALTER_COLUMN_NOT_NULL, ALTER_TABLE_ALTER_COLUMN_NULL, ALTER_TABLE_ALTER_COLUMN_RENAME, ALTER_TABLE_ALTER_COLUMN_SELECTIVITY, ALTER_TABLE_DROP_COLUMN, ALTER_TABLE_DROP_CONSTRAINT, ALTER_TABLE_RENAME, ALTER_TABLE_RENAME_CONSTRAINT, ALTER_TABLE_SET_REFERENTIAL_INTEGRITY, ALTER_USER_ADMIN, ALTER_USER_RENAME, ALTER_USER_SET_PASSWORD, ALTER_VIEW, ANALYZE, BACKUP, BEGIN, CALL, CHECKPOINT, CHECKPOINT_SYNC, COMMENT, COMMIT, COMMIT_TRANSACTION, CREATE_AGGREGATE, CREATE_ALIAS, CREATE_CONSTANT, CREATE_DOMAIN, CREATE_INDEX, CREATE_LINKED_TABLE, CREATE_ROLE, CREATE_SCHEMA, CREATE_SEQUENCE, CREATE_TABLE, CREATE_TRIGGER, CREATE_USER, CREATE_VIEW, DEALLOCATE, DELETE, DROP_AGGREGATE, DROP_ALIAS, DROP_ALL_OBJECTS, DROP_CONSTANT, DROP_DOMAIN, DROP_INDEX, DROP_ROLE, DROP_SCHEMA, DROP_SEQUENCE, DROP_TABLE, DROP_TRIGGER, DROP_USER, DROP_VIEW, EXECUTE, EXPLAIN, GRANT, INSERT, MERGE, NO_OPERATION, PREPARE, PREPARE_COMMIT, REPLACE, REVOKE, ROLLBACK, ROLLBACK_TO_SAVEPOINT, ROLLBACK_TRANSACTION, RUNSCRIPT, SAVEPOINT, SCRIPT, SELECT, SET, SET_AUTOCOMMIT_FALSE, SET_AUTOCOMMIT_TRUE, SHUTDOWN, SHUTDOWN_COMPACT, SHUTDOWN_DEFRAG, SHUTDOWN_IMMEDIATELY, TRUNCATE_TABLE, UNKNOWN, UPDATE

字段
限定符和类型	字段和说明
`protected Session`	`session` The session.
`protected long`	`startTimeNanos` The last start time.

方法概要

所有方法实例方法抽象方法具体方法
限定符和类型	方法和说明
`void`	`cancel()` Cancel the statement if it is still processing.
`boolean`	`canReuse()` Whether the command is already closed (in which case it can be re-used).
`protected void`	`checkCanceled()` Check if this command has been canceled, and throw an exception if yes.
`void`	`close()` Close the statement.
`ResultInterface`	`executeQuery(int maxrows, boolean scrollable)` Execute a query and return the result.
`int`	`executeUpdate()` Execute the statement
`ResultInterface`	`getMetaData()` Get an empty result set containing the meta data of the result.
`abstract ArrayList<? extends ParameterInterface>`	`getParameters()` Get the list of parameters.
`boolean`	`isCacheable()`
`abstract boolean`	`isQuery()` Check if this command is a query.
`abstract boolean`	`isReadOnly()` Check if this command is read only.
`abstract boolean`	`isTransactional()` Check if this command is transactional.
`abstract void`	`prepareJoinBatch()` Prepare join batching.
`ResultInterface`	`query(int maxrows)` Execute a query statement, if this is possible.
`abstract ResultInterface`	`queryMeta()` Get an empty result set containing the meta data.
`void`	`reuse()` The command is now re-used, therefore reset the canReuse flag, and the parameter values.
`String`	`toString()`
`int`	`update()` Execute an updating statement (for example insert, delete, or update), if this is possible.

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.command.CommandInterface
getCommandType

- 字段详细资料
  - session
```
protected final Session session
```
    The session.
  - startTimeNanos
```
protected long startTimeNanos
```
    The last start time.
- 方法详细资料
  - isTransactional
```
public abstract boolean isTransactional()
```
    Check if this command is transactional. If it is not, then it forces the current transaction to commit.
    
    返回:
    
    true if it is
  - isQuery
```
public abstract boolean isQuery()
```
    Check if this command is a query.
    
    指定者:
    
    isQuery 在接口中 CommandInterface
    
    返回:
    
    true if it is
  - prepareJoinBatch
```
public abstract void prepareJoinBatch()
```
    Prepare join batching.
  - getParameters
```
public abstract ArrayList<? extends ParameterInterface> getParameters()
```
    Get the list of parameters.
    
    指定者:
    
    getParameters 在接口中 CommandInterface
    
    返回:
    
    the list of parameters
  - isReadOnly
```
public abstract boolean isReadOnly()
```
    Check if this command is read only.
    
    返回:
    
    true if it is
  - queryMeta
```
public abstract ResultInterface queryMeta()
```
    Get an empty result set containing the meta data.
    
    返回:
    
    an empty result set
  - update
```
public int update()
```
    Execute an updating statement (for example insert, delete, or update), if this is possible.
    
    返回:
    
    the update count
    
    抛出:
    
    DbException - if the command is not an updating statement
  - query
```
public ResultInterface query(int maxrows)
```
    Execute a query statement, if this is possible.
    
    参数:
    
    maxrows - the maximum number of rows returned
    
    返回:
    
    the local result set
    
    抛出:
    
    DbException - if the command is not a query
  - getMetaData
```
public final ResultInterface getMetaData()
```
    从接口复制的说明: CommandInterface
    
    Get an empty result set containing the meta data of the result.
    
    指定者:
    
    getMetaData 在接口中 CommandInterface
    
    返回:
    
    the empty result
  - checkCanceled
```
protected void checkCanceled()
```
    Check if this command has been canceled, and throw an exception if yes.
    
    抛出:
    
    DbException - if the statement has been canceled
  - executeQuery
```
public ResultInterface executeQuery(int maxrows,
                                    boolean scrollable)
```
    Execute a query and return the result. This method prepares everything and calls query(int) finally.
    
    指定者:
    
    executeQuery 在接口中 CommandInterface
    
    参数:
    
    maxrows - the maximum number of rows to return
    
    scrollable - if the result set must be scrollable (ignored)
    
    返回:
    
    the result set
  - executeUpdate
```
public int executeUpdate()
```
    从接口复制的说明: CommandInterface
    
    Execute the statement
    
    指定者:
    
    executeUpdate 在接口中 CommandInterface
    
    返回:
    
    the update count
  - close
```
public void close()
```
    从接口复制的说明: CommandInterface
    
    Close the statement.
    
    指定者:
    
    close 在接口中 CommandInterface
  - cancel
```
public void cancel()
```
    从接口复制的说明: CommandInterface
    
    Cancel the statement if it is still processing.
    
    指定者:
    
    cancel 在接口中 CommandInterface
  - toString
```
public String toString()
```
    覆盖:
    
    toString 在类中 Object
  - isCacheable
```
public boolean isCacheable()
```
  - canReuse
```
public boolean canReuse()
```
    Whether the command is already closed (in which case it can be re-used).
    
    返回:
    
    true if it can be re-used
  - reuse
```
public void reuse()
```
    The command is now re-used, therefore reset the canReuse flag, and the parameter values.

类 Command

字段概要

从接口继承的字段 org.h2.command.CommandInterface

方法概要

从类继承的方法 java.lang.Object

从接口继承的方法 org.h2.command.CommandInterface

字段详细资料

session

startTimeNanos

方法详细资料

isTransactional

isQuery

prepareJoinBatch

getParameters

isReadOnly

queryMeta

update

query

getMetaData

checkCanceled

executeQuery

executeUpdate

close

cancel

toString

isCacheable

canReuse

reuse