Supplying parameters at runtime

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To create parameters at runtime, you can use the:

  • ParamByName method to assign values to a parameter based on its name.
  • Params property to assign values to a parameter based on the parameter’s ordinal position within the SQL statement.
  • Params.ParamValues property to assign values to one or more parameters in a single command line, based on the name of each parameter set. This method uses variants and avoids the need to cast values.
In dialect 3, parameter names passed to functions are case-sensitive.

For all of the examples below, assume the SQL property contains the SQL statement below. All three parameters used are of data type ftString.

<psource lang=sql> INSERT INTO "COUNTRY.DB" (Name, Capital, Continent) VALUES (:Name, :Capital, :Continent) </source>

The following code uses ParamByName to assign the text of an edit box to the Capital parameter:

IBQuery1.ParamByName(‘Capital’).AsString := Edit1.Text;

The same code can be rewritten using the Params property, using an index of 1 (the Capital parameter is the second parameter in the SQL statement):

IBQuery1.Params[1].AsString := Edit1.Text;

The command line below sets all three parameters at once, using the Params.ParamValues property:

IBQuery1.Params.ParamValues[‘Country;Capital;Continent’] :=
  VarArrayOf([Edit1.Text, Edit2.Text, Edit3.Text]);

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