Does anyone know how to add a column to a DBISAM table using program code?

On 10/19/2015 1:14 PM, Max Stewart wrote:
> Does anyone know how to add a column to a DBISAM table using program code?
>

Yes. Did you look at the manual  ?

I would suggest start with the "Creating and Altering Tables" section there

http://www.elevatesoft.com/manual?action=viewtopic&id=dbisam4&product=rsdelphiwin32&version=10S&topic=Creating_Altering_Tables

Raul

Max,

<< Does anyone know how to add a column to a DBISAM table using program code? >>

As Raul suggests, there's an example at that link, specifically this one:

The following example shows how to alter the local "customer" table's structure using the AlterTable method without any additional parameters. In this example we want to add a LastSaleAmount (a BCD field) to this table's structure in front of the LastSaleDate field and then add a secondary index on this new LastSaleAmount field to speed up filtering in SQL queries:

Customer Table Structure Before Alteration

Field #    Name              DataType     Size
----------------------------------------------
1          CustomerID        ftString     10
2          CustomerName      ftString     30
3          ContactName       ftString     30
4          Phone             ftString     10
5          Fax               ftString     10
6          EMail             ftString     30
7          LastSaleDate      ftDate       0       
   
Index Name      Fields In Index      Options
----------------------------------------------
(none)          CustomerID           ixPrimary

begin
  with MyTable do
     begin
     DatabaseName:='c:\temp';
     TableName:='customer';
     { Always make sure the table is closed first }
     Active:=False;
     { Update the field definitions using the
       existing field definitions from the table }
     FieldDefs.Update;
     { Same for the index definitions }
     IndexDefs.Update;
     { Now insert the new field definition.  Notice
       the index position of 6 which is 0-based and
       the field number of 8 which is 1-based and
       equal to the next available field number since
       there are currently 7 field definitions for this
       table }
     FieldDefs.Insert(6,8,'LastSaleAmount',ftBCD,2,False);
     IndexDefs.Add('LastSaleAmount','LastSaleAmount',[]);
     { Now alter the table's structure }
     AlterTable;
     end;
end;

Customer Table Structure After Alteration

Field #    Name              DataType     Size
----------------------------------------------
1          CustomerID        ftString     10
2          CustomerName      ftString     30
3          ContactName       ftString     30
4          Phone             ftString     10
5          Fax               ftString     10
6          EMail             ftString     30
7          LastSaleAmount    ftBCD        2
8          LastSaleDate      ftDate       0       
   
Index Name      Fields In Index      Options
----------------------------------------------
(none)          CustomerID           ixPrimary
LastSaleDate    LastSaleDate         (none)

If you just want to add, instead of insert, a field definition, then just use the Add method instead of the Insert method, and leave off the index position parameter.

Tim Young
Elevate Software
www.elevatesoft.com

Hi Max,

> Does anyone know how to add a column to a DBISAM table using program code?

Personally, I like to add my tables in my project using SQL. This way I
can test outside as well using DBSYS to make sure all is OK.

ie:

procedure TForm1.addfield;
begin
MySQL.SQL.text = 'Alter Table MyTable Add "MyNewField" Varchar(10)';
MySQL.execsql;
end;

You can insert / redefine indexes as well using this.

Just another option...

Cheers

Adam.

Max Stewart wrote:

> Does anyone know how to add a column to a DBISAM table using program
> code?

If you want the DBISAM versions of my EDB file, let me know. I don't
have them in a separate file at the moment as I just copy the unit and
customise, but it wouldn't be hard to dig up (and I should probably do
it anyway).

--

Matthew Jones