Creating a sequence for a varchar2 field in Oracle

Question

I want to create a sequence for this varchar. It would have been easier had it been a number instead of varchar. In that case, I could do

seq_no := se

Answer 1

Sequences are purely numeric. However, you need a trigger anyway, so simply adapt such trigger to insert the desired prefix:

CREATE OR REPLACE TRIGGER FOO_TRG1
    BEFORE INSERT
    ON FOO
    REFERENCING NEW AS NEW OLD AS OLD
    FOR EACH ROW
BEGIN
    IF :NEW.FOO_ID IS NULL THEN
        SELECT 'A' || TO_CHAR(FOO_SEQ1.NEXTVAL, 'FM0000000') INTO :NEW.FOO_ID FROM DUAL;
    END IF;
END FOO_TRG1;
/
ALTER TRIGGER FOO_TRG1 ENABLE;