Package com.mckoi.database.interpret

Class Show

java.lang.Object

com.mckoi.database.interpret.Statement

com.mckoi.database.interpret.Show

public class Show
extends Statement

Statement that handles SHOW and DESCRIBE sql commands.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) Expression[]	args	Arguments of the show statement.
(package private) static int	CONNECTION_INFO
(package private) static int	CONNECTIONS
(package private) static int	DESCRIBE_TABLE
(package private) static int	PRODUCT
(package private) java.lang.String	show_type	The type of information that we are to show.
(package private) static int	STATUS
(package private) java.lang.String	table_name	The name the table that we are to update.
(package private) static int	TABLES
(package private) SearchExpression	where_clause	The search expression for the show statement (where clause).

Fields inherited from class com.mckoi.database.interpret.Statement

cmd, database, query, table_list, user

Constructor Summary

Constructors

Constructor	Description
Show()

Method Summary

Modifier and Type	Method	Description
(package private) TemporaryTable	createEmptyTable(Database d, java.lang.String name, java.lang.String[] cols)	Convenience, creates an empty table with the given column names.
Table	evaluate()	Evaluates the statement and returns a table that represents the result set.
void	prepare()	Prepares the statement with the given Database object.

Methods inherited from class com.mckoi.database.interpret.Statement

addTable, Debug, existsTableWithColumn, findTableInQuery, findTableWithColumn, init, reset, resolveAgainstAliases, resolveColumn, resolveExpression, resolveTableName, resolveTree, resolveVariableName

Methods inherited from class java.lang.Object

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

Field Detail

TABLES

static final int TABLES

See Also:

Constant Field Values

STATUS

static final int STATUS

See Also:

Constant Field Values

DESCRIBE_TABLE

static final int DESCRIBE_TABLE

See Also:

Constant Field Values

CONNECTIONS

static final int CONNECTIONS

See Also:

Constant Field Values

PRODUCT

static final int PRODUCT

See Also:

Constant Field Values

CONNECTION_INFO

static final int CONNECTION_INFO

See Also:

Constant Field Values

table_name

java.lang.String table_name

The name the table that we are to update.

show_type

java.lang.String show_type

The type of information that we are to show.

args

Expression[] args

Arguments of the show statement.

where_clause

SearchExpression where_clause

The search expression for the show statement (where clause).

Constructor Detail

Show

public Show()

Method Detail

createEmptyTable

TemporaryTable createEmptyTable(Database d,
                                java.lang.String name,
                                java.lang.String[] cols)
                         throws DatabaseException

Convenience, creates an empty table with the given column names.

Throws:

DatabaseException

prepare

public void prepare()
             throws DatabaseException

Description copied from class: Statement

Prepares the statement with the given Database object. This is called before the statement is evaluated. The prepare statement queries the database and resolves information about the statement (for example, it resolves column names and aliases and determines the tables that are touched by this statement so we can lock the appropriate tables before we evaluate).

NOTE: Care must be taken to ensure that all methods called here are safe in as far as modifications to the data occuring. The rules for safety should be as follows. If the database is in EXCLUSIVE mode, then we need to wait until it's switched back to SHARED mode before this method is called. All collection of information done here should not involve any table state info. except for column count, column names, column types, etc. Queries such as obtaining the row count, selectable scheme information, and certainly 'getCellContents' must never be called during prepare. When prepare finishes, the affected tables are locked and the query is safe to 'evaluate' at which time table state is safe to inspect.

Specified by:

prepare in class Statement

Throws:

DatabaseException

evaluate

public Table evaluate()
               throws DatabaseException

Description copied from class: Statement

Evaluates the statement and returns a table that represents the result set. This is called after 'prepare'.

Specified by:

evaluate in class Statement

Throws:

DatabaseException