{"id":18771,"date":"2022-11-01T22:33:40","date_gmt":"2022-11-01T17:03:40","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-display-database-structure-from-delphi-rad-studio\/"},"modified":"2022-11-01T22:33:40","modified_gmt":"2022-11-01T17:03:40","slug":"solved-display-database-structure-from-delphi-rad-studio","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-display-database-structure-from-delphi-rad-studio\/","title":{"rendered":"[Solved] Display database structure from Delphi (rad studio)"},"content":{"rendered":"

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As already explained to you in comments, your while<\/code> loop should look something like this:<\/p>\n

 while **not** FData.FDQuery1.Eof do **begin**\n    ShowMessage(FData.FDQuery1.Fields[0].ToString);\n    **FData.FDQuery1.Next;**\n end;\n<\/code><\/pre>\n
(minus the asterisks, of course).  However, that would not overcome the problem that your SQL is incorrect.<\/p>\n
So, try this instead:<\/p>\n
    \n
  1. \n
    In a new Delphi project, place a TFDConnection, TFDQuery, TDataSource,
    \nTDataSource and a TListBox on a form.  Save the form and project.<\/p>\n<\/li>\n
  2. \n
    Double-click FDConnection1 to pop up its connection editor and configure
    \nit so you can successfully connect it to your database.<\/p>\n<\/li>\n
  3. \n
    Connect DBGrid1 to DataSource1 and Datasource1 to FDQuery1.<\/p>\n<\/li>\n
  4. \n
    Add the code below to the form’s OnCreate event.<\/p>\n<\/li>\n
  5. \n
    Compile and run.<\/p>\n<\/li>\n
  6. \n
    You should immediately see the cause of your problem.  As the error message
    \ntold you, there is no strDBName field in the INFORMATION_SCHEMA.TABLES table.<\/p>\n<\/li>\n<\/ol>\n
    So you need to backtrack to the MySQL online help, starting e.g. here<\/p>\n
    https:\/\/dev.mysql.com\/doc\/refman\/5.7\/en\/tables-table.html<\/a><\/p>\n
    and work out exactly what it is that you are looking for,
    \nif you don’t already know, and how to get it from within your project.<\/p>\n
    Btw, if you are not sure what you are doing, you should always try your SQL first in the MySql Workbench utility.<\/p>\n
    Code<\/p>\n
      FDQuery1.SQL.Text := 'SELECT * FROM INFORMATION_SCHEMA.TABLES';\n  FDQuery1.Open;\n  FDQuery1.GetFieldNames(ListBox1.Items);\n<\/code><\/pre>\n
    I have a MySql database called ‘MATestDB’.  To get a list of the fields (columns) in its tables, I would add this code to TForm1.FormCreate:<\/p>\n
      FDQuery2.SQL.Text := 'select * from information_schema.columns where table_schema=\"\"MATestDB''';\n  FDQuery2.Open;\n<\/code><\/pre>\n
    If you want FDQuery2 and its grid to track the selected table in FDQuery1, you can use code like the following to set up a master-detail<\/code> relationship between them:<\/p>\n
    procedure TForm1.FormCreate(Sender: TObject);\nbegin\n  FDQuery1.SQL.Text := 'SELECT * FROM INFORMATION_SCHEMA.TABLES';\n\n  FDQuery2.SQL.Text := 'select table_schema, table_name, column_name, data_type, character_maximum_length, ordinal_position from information_schema.columns where table_schema = :Table_Schema and table_name = :Table_Name';\n  FDQuery2.IndexFieldNames := 'table_schema;table_name;ordinal_position';\n  FDQuery2.MasterFields := 'table_schema;table_name';\n  FDQuery2.MasterSource := DataSource1;\n\n  FDQuery1.Open;\n  FDQuery1.GetFieldNames(ListBox1.Items);\n\n  FDQuery2.Open;\n  FDQuery2.GetFieldNames(ListBox2.Items);\n\nend;\n<\/code><\/pre>\n
    Btw, you will not be able to get schema info for a Paradox database in the same way, but you should be able to google how to find out what information you want to gather from Paradox.<\/p>\n
    Btw #2: In the Sql you quoted in your deleted answer, one problem would be the reference to DBGrid2.SelectedField.ToString<\/code>.  If DBGrid2 gets its data from FDQuery2, then you may have meant DBGrid**1**.SelectedField.ToString<\/code>.  If you are still having problem with that, I suggest you ask about it in a new q, but make sure you include all the code necessary to reproduce the problem.<\/p>\n<\/p><\/div>\n
    <\/div>\n<\/div>\n
                1<\/span> <\/p><\/div>\n<\/div>\n
    [ad_2]<\/p>\n
    solved Display database structure from Delphi (rad studio) <\/p>\n","protected":false},"excerpt":{"rendered":"
    [ad_1] As already explained to you in comments, your while loop should look something like this: while **not** FData.FDQuery1.Eof do **begin** ShowMessage(FData.FDQuery1.Fields[0].ToString); **FData.FDQuery1.Next;** end; (minus the asterisks, of course). However, that would not overcome the problem that your SQL is incorrect. So, try this instead: In a new Delphi project, place a TFDConnection, TFDQuery, TDataSource, … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[740,340,4522,4521],"class_list":["post-18771","post","type-post","status-publish","format-standard","hentry","category-solved","tag-delphi","tag-mysql","tag-paradox","tag-rad"],"yoast_head":"\n[Solved] Display database structure from Delphi (rad studio) - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-display-database-structure-from-delphi-rad-studio\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Display database structure from Delphi (rad studio) - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] As already explained to you in comments, your while loop should look something like this: while **not** FData.FDQuery1.Eof do **begin** ShowMessage(FData.FDQuery1.Fields[0].ToString); **FData.FDQuery1.Next;** end; (minus the asterisks, of course). 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However, that would not overcome the problem that your SQL is incorrect. So, try this instead: In a new Delphi project, place a TFDConnection, TFDQuery, TDataSource, ... 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