[英]Is there a way to set AUTO_INCREMENT property on existing table column in Vertica?
Suppose I have a simple table: 假设我有一个简单的表:
CREATE TABLE user(
id INT NOT NULL PRIMARY KEY,
name VARCHAR(32) NOT NULL,
)
Is there a way to alter this table so id
will become AUTO_INCREMENT field? 有没有办法改变这个表,所以id
将成为AUTO_INCREMENT字段?
I tried the following with no luck: 我试了以下没有运气:
Thanks! 谢谢!
I would try to just rank the rows, and use the sequence for future inserts. 我会尝试对行进行排名,并将序列用于将来的插入。
\set AUTOCOMMIT 'on'
CREATE TABLE t1 (
val char(1)
);
INSERT INTO t1 VALUES ('a');
INSERT INTO t1 VALUES ('b');
INSERT INTO t1 VALUES ('c');
INSERT INTO t1 VALUES ('d');
CREATE TABLE t2 (
id int,
val char(1)
);
INSERT INTO t2 (val, id)
SELECT val, RANK() OVER (ORDER BY val) as id
FROM t1;
SELECT * FROM t2;
We get: 我们得到:
id | val ----+----- 1 | a 3 | c 2 | b 4 | d
Success! 成功!
Let's prepare the table for future inserts: 让我们为将来的插入准备表格:
-- get the value to start sequence at
SELECT MAX(id) FROM t2;
-- create the sequence
CREATE SEQUENCE seq1 START 5;
-- syntax as of 6.1
-- modify the column to add next value for future rows
ALTER TABLE t2 ALTER COLUMN id SET DEFAULT NEXTVAL('seq1');
Quick test: 快速测试:
INSERT INTO t2 (val) VALUES ('e');
INSERT INTO t2 (val) VALUES ('f');
SELECT * FROM t2;
We get: 我们得到:
id | val ----+----- 4 | d 2 | b 3 | c 6 | f 1 | a 5 | e
Hope this helps. 希望这可以帮助。
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