--你要想实现那样的话,可以通过trigger来做: CREATE OR REPLACE TRIGGER trg_testa BEFORE INSERT ON testa FOR EACH ROW BEGIN :NEW.b:=:NEW.a; END;/* 向testa表插入数据 */ INSERT INTO testa(a) VALUES(myseq.NEXTVAL) ; INSERT INTO testa(a) VALUES(myseq.NEXTVAL); INSERT INTO testa(a) VALUES(myseq.NEXTVAL) ;
As defined, the first reference to order_seq.NEXTVAL returns the value 1. Each subsequent statement that references order_seq.NEXTVAL generates the next sequence number (2, 3, 4,. . .). The pseudo-column NEXTVAL can be used to generate as many new sequence numbers as necessary. However, only a single sequence number can be generated for each row. In other words, if NEXTVAL is referenced more than once in a single statement, then the first reference generates the next number, and all subsequent references in the statement return the same number.
CREATE OR REPLACE TRIGGER trg_testa
BEFORE INSERT ON testa
FOR EACH ROW
BEGIN
:NEW.b:=:NEW.a;
END;/* 向testa表插入数据 */
INSERT INTO testa(a) VALUES(myseq.NEXTVAL) ;
INSERT INTO testa(a) VALUES(myseq.NEXTVAL);
INSERT INTO testa(a) VALUES(myseq.NEXTVAL) ;