postgres 冲突定义--upset

01，场景定义

　　一般某些值可能设置唯一键导致插入数据出错

02，场景复现

--创建表
CREATE TABLE  kingle_study_5 (
    name VARCHAR(200) PRIMARY KEY,
    time INT4,
    insert_time TIMESTAMP(0) WITHOUT TIME ZONE 
);

数据植入

INSERT INTO kingle_study_5 VALUES 
('a',1),('b',2),('a',1);

 

 

 执行的时候就会发现一整个这个问题，主键冲突

03，upset 来袭

　　

语法定义在insert 下面

Command:     INSERT
Description: create new rows in a table
Syntax:
[ WITH [ RECURSIVE ] with_query [, ...] ]
INSERT INTO table_name [ AS alias ] [ ( column_name [, ...] ) ]
    [ OVERRIDING { SYSTEM | USER } VALUE ]
    { DEFAULT VALUES | VALUES ( { expression | DEFAULT } [, ...] ) [, ...] | query }
    [ ON CONFLICT [ conflict_target ] conflict_action ]
    [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]

where conflict_target can be one of:

    ( { index_column_name | ( index_expression ) } [ COLLATE collation ] [ opclass ] [, ...] ) [ WHERE index_predicate ]
    ON CONSTRAINT constraint_name

and conflict_action is one of:

    DO NOTHING
    DO UPDATE SET { column_name = { expression | DEFAULT } |
                    ( column_name [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) |
                    ( column_name [, ...] ) = ( sub-SELECT )
                  } [, ...]
              [ WHERE condition ]

　001，冲突更新操作

INSERT INTO kingle_study_5 (name,time) VALUES 
('b',2),('a',1)
ON conflict(name)    -- 定义冲突的键
DO UPDATE SET        -- 冲突设置
time = kingle_study_5.time + EXCLUDED.time,insert_time= now();

　　我们查询看看是不是成功了

　

 

再执行一次 同样的操作

 

 

 

 发现每次  插入后更新 新的值

　　　002，冲突不更新操作　

 

 数据不做任何变化

来自 《postgres 实战》