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TFDCommand component

Table of Contents

Types of Command

The TFDCommand component is used to execute SQL queries. It is not descended from TDataSet so it is valid to use only for executing SQL queries that do not return datasets.

Table 3.5. TFDCommand component main properties

Property Purpose
Connection Reference to the TFDConnection component
Transaction The transaction within which the SQL command will be executed
CommandKind Type of command. The types are described in the section below.
CommandText SQL query text


Types of Command

Usually, the command type is determined automatically from the text of the SQL statement. The following values are available for the property TFDCommand.CommandKind to cater for cases where the internal parser might be unable to make correct, unambiguous assumptions based on the statement text alone:

  • skUnknown—unknown. Tells the internal parser to determine the command type automatically from its analysis of the text of the command
  • skStartTransaction—a command for starting a transaction
  • skCommit—a command for ending and committing a transaction
  • skRollback—a command for ending and rolling back a transaction
  • skCreate—a CREATE … command for creating a new metadata object
  • skAlter—an ALTER … command for altering a metadata object
  • skDrop—a DROP … command for deleting a metadata object
  • skSelect—a SELECT command for retrieving data
  • skSelectForLock—a SELECT … WITH LOCK command for locking the selected rows
  • skInsert—an INSERT … command for inserting a new record
  • skUpdate—an UPDATE … command for modifying records
  • skDelete—a DELETE … command for deleting records
  • skMerge—a MERGE INTO … command
  • skExecute—an EXECUTE PROCEDURE or or EXECUTE BLOCK command
  • skStoredProc—a stored procedure call
  • skStoredProcNoCrs—a call to a stored procedure that does not return a cursor
  • skStoredProcWithCrs—a call to a stored procedure that returns a cursor

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