Set ParamCheck to specify whether or not the Parameters property is initialized using ":Param" style parameters in an SQL statement specified in the CommandText property. If the SQL statement in CommandText only contains "?" style parameters, the Parameters property will only be initialized if the OLE DB provider returns parameter information for an SQL command. Otherwise, the parameters must be explicitly created using the CreateParameter method (TParameter).
When ParamCheck is true, a parameter is generated for each ":Param" style parameter in the SQL statement.
The default value of ParamCheck is true.
This property is useful for data definition language (DDL) statements that contain parameters as part of the DDL statement and that are not parameters for the ADO dataset component. For example, the DDL statement to create a stored procedure may contain parameter statements that are part of the stored procedure. Set ParamCheck to false to prevent these parameters from being mistaken for parameters of the ADO dataset component executing the DDL statement.
当paramcheck为false时，如果开发的时候已经设置好parameters，则在sql.add之前，parameters为开发时设定的值（即使执行了sql.clear），执行sql.add之后，parameters为空。