Pezzzz Pezzzz - 5 months ago 20
SQL Question

How to add a 'Boolean' column to ms-access via SQL in vb.net

I am trying to add a

Boolean
column to a table in ms-access using SQL. I am using JET, here are the the SQL queries I have tried.

Query = "ALTER TABLE tabDatafiveMinutely ADD CON0001 BOOLEAN DEFAULT FALSE"
Query = "ALTER TABLE tabDatafiveMinutely ADD CON0001 BOOLEAN"


The error I am getting is 'Syntax error in field definition'

Thanks for your help

EDIT:

I would now like to make the default
null
rather than
false
. I have tried
default null
and this still gives me
false
, can anyone help with this?

RESULT:

An ms-access database can only take
true
and
false
and not null. Therefore I have decided to use and
integer
instead.

Answer

The equivalent SQL type of a Yes/No column is BIT

ALTER TABLE tabDatafiveMinutely
    ADD COLUMN CON0001 BIT   DEFAULT 0   NOT NULL

Microsoft's documentation says

Note
The DEFAULT statement can be executed only through the Jet OLE DB provider and ADO. It will return an error message if used through the Access SQL View user interface.


As @Pere points out, Jet Engine (Access' query engine) does not apply the DEFAULT value to existing rows. You must run an UPDATE statement after altering the table.

UPDATE tabDatafiveMinutely SET CON0001 = 0 WHERE CON0001 IS NULL