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Editorial Team
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Asked: 2026-06-15T01:02:25+00:00

I am trying to add a Boolean column to a table in ms-access using

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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.

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1 Answer

  1. Editorial Team

    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
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