如何在Delphi中的SQL中使用节中的变量

Question

source:= tabledemap.FieldByName('table source').AsString + '('+ tabledemap.FieldByName('colonne source').AsString+')';
  showmessage(source)  ;

The source value is the column: a.name (firsatname) I want to insert in this column the string 't' But the problem I want to use the value of the source variable in a sql request like this

 FDQuery6.SQL.Add ('INSERT INTO  source  Values ( "t" ) ');

     FDQuery6.Execute;

      showmessage('row inserted');

But the program fails to use the text of the value of the source variable and think that source is a name of a table and displays to me

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Notification des exceptions du débogueur
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Le projet x a déclenché la classe d'exception EMySQLNativeException avec le message '[FireDAC][Phys][MySQL] Table 'a.source' doesn't exist'.

I have tried "source" , +source+ but it won't work also . If anyone can help me to use the text of the source variable in the SQL query I will be grateful.

Answer 1

In FireDAC you can paremetrize table and field names by using preprocessor macros. For example:

FDQuery.SQL.Text := 'INSERT INTO &TableName (&FieldName) VALUES "ConstValue"';
FDQuery.MacroByName('TableName').AsIdentifier := 'MyTable';
FDQuery.MacroByName('FieldName').AsIdentifier := 'MyField';
FDQuery.ExecSQL;

For details about this kind of macros, see the substitution variables topic.