Before you can use writetext to enter text data or readtext to read it, you must initialize the text column. For details, see readtext and writetext in Reference Manual: Commands.
Using update to replace existing text, unitext, and image data with NULL reclaims all allocated data pages except the first page, which remains available for future use of writetext. To deallocate all storage for the row, use delete to remove the entire row.
There are restrictions for using readtext and writetext on a column defined for unitext. For more information see the “Usage” sections under readtext and writetext in the Reference Manual: Commands.
