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.
Author:
Tobias Downer
  • Constructor Details

    • Show

      public Show()
  • Method Details

    • 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