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Copying data from varchar to blob field

Hi,

I need to change a field's data type from varchar to blob, while retaining the data. I'm following the 6-step procedure (which I've also read from this site)

1. create temp varchar
2. copy data from original varchar to temp column
3. drop original varchar
4. create blob field
5. copy data from temp varchar to blob
6. drop temp varchar

I am having problem with step 5. Copying data from varchar to blob is not as straightforward as using an Update statement. I know I should be using blob cursor, and I've already gathered sql statements to create & insert record to blob field. But what's missing is how to iterate through all the records. And the sql statements are not executing successfully (I'm using IBExpert)

DECLARE blob_cur CURSOR FOR
INSERT BLOB description INTO pr_product;

OPEN blob_cur INTO description;

INSERT CURSOR blob_cur VALUES (temp_desc);

CLOSE blob_cur;

Thanks for your time,

estela : )

ASKER CERTIFIED SOLUTION

BAlexandrov

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BAlexandrov

If you use Firebird you can do directly
"update my_table set blob_collumn = varchar_collumn"
Next is an example of stored procedure that you can alter to your needs.
If we have this table:

CREATE TABLE NEW_TABLE (
ID INTEGER NOT NULL,
PRICE NUMERIC(15,2),
CODE INTEGER,
BL BLOB SUB_TYPE 2 SEGMENT SIZE 4096,
VAR VARCHAR(100)
);

ALTER TABLE NEW_TABLE ADD PRIMARY KEY (ID);

And you want to copy var collumn to bl collumn

CREATE PROCEDURE NEW_PROCEDURE
AS
declare variable var_temp varchar(100);
declare variable id int;
begin
for Select id,var from new_table
into :id,:var_temp
do
Begin
update new_table set bl = :var_temp where id = :id;
end
end

Then execute it

emayuga

ASKER

Unfortunately, I am just using IB6..
Thanks for the sample script : )
However, I am encountering an error in declaring a blob cursor. Maybe you can help with this one too..

I have a PR_PRODUCT table containing the ff. fields:
ID INTEGER NOT NULL,
Description BLOB,
Temp_Desc VARCHAR(125),

Here's the procedure:

CREATE PROCEDURE Populate_Prod_Desc
AS
declare variable var_temp varchar(125);
declare variable id int;
declare blob_cur cursor for
insert blob description into pr_product;

begin
open blob_cur into description;
for Select id, temp_desc from pr_product
into :id, :var_temp
do
Begin
insert cursor blob_cur values (:var_temp) where id = :id;
end
close blob_cur;
end

I am encountering the error "Token Unknown - line 5, char 9. blob_cur" when executing this statement. There's probably something wrong with the syntax...?

Thanks,
estela : )

BAlexandrov

I totally cannot understand what you are trying to do... :(

Plase read the manuals about working with cursors

kacor

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