Restrictions for Modifying text and image Columns

Restrictions that apply when you modify text and image columns.

  • You can only add text or image columns that accept null values.

    To add a text or image column so it contains only non-null values, first add a column that only accepts null values and then update it to the non-null values.

  • You can modify a column from text datatype only to the following datatypes:

    • [n]char

    • [n]varchar

    • unichar

    • univarchar

    • nchar

    • nvarchar

  • You can modify a column from image datatype only to binary or varbinary.

  • You cannot add a new text or image column and then drop an existing text or image column in the same statement.

  • You cannot modify a column to either text or image datatype.

Parent topic: alter table