Question

我正在尝试编写一个查询，以防止插入重复的行，如下所示

INSERT INTO RSS_SETTING_ADMIN (ID_PRODUCT , ID_RSS , ID_CATEGORY , ID_TYPE_USER)
VALUES (384 , 3, 283 , 1)WHERE NOT EXISTS 
(SELECT * FROM RSS_SETTING_ADMIN 
WHERE ID_PRODUCT = 384 , ID_RSS = 3 , ID_CATEGORY = 283, ID_TYPE_USER = 1)

但我收到了

SQL命令未正确结束

错误

Answer 1

你的命令应该是：

INSERT INTO RSS_SETTING_ADMIN (ID_PRODUCT , ID_RSS , ID_CATEGORY , ID_TYPE_USER) 
SELECT 384 , 3, 283 , 1 FROM  DUAL
WHERE NOT EXISTS 
(SELECT * FROM RSS_SETTING_ADMIN 
  WHERE ID_PRODUCT = 384 
        AND ID_RSS = 3 
        AND ID_CATEGORY = 283 
        AND ID_TYPE_USER = 1
);

我还记得你不足以防止重复的行，你需要一个唯一的密钥。

Answer 2

您应该将查询更改为此

INSERT INTO RSS_SETTING_ADMIN (ID_PRODUCT , ID_RSS , ID_CATEGORY , ID_TYPE_USER)
select 384 , 3, 283 , 1 
from dual 
WHERE NOT EXISTS (SELECT * 
                  FROM RSS_SETTING_ADMIN 
                  WHERE ID_PRODUCT = 384 and ID_RSS = 3 
                         and ID_CATEGORY = 283 and ID_TYPE_USER = 1
                  );

Answer 3

如果要阻止插入重复值，则应在表上使用唯一约束/索引：

alter table RSS_SETTING_ADMIN
    add constraint unq_RSS_SETTING_ADMIN_4 unique(id_product, id_rss, id_category, id_type_user);

让数据库维护关系完整性而不是应用程序是一种更好的方法。

如果您仍想使用not exists，我建议：

insert intoRSS_SETTING_ADMIN (ID_PRODUCT , ID_RSS , ID_CATEGORY , ID_TYPE_USER)
    select x.id_product, x.id_rss, x.id_category, x.id_type_user
    from (select 384 as id_product, 3 as id_rss, 283 as id_category, 1 as id_type_user
          from dual
         ) x
    where not exists (select 1
                      from  RSS_SETTING_ADMIN rsa
                      where rsa.id_product = x.id_product and 
                            rsa.id_rss = x.id_rss and
                            rsa.id_category = x.id_category and 
                            rsa.id_type_user = x.id_type_user
                      );

使用此结构，值只包含在查询中一次，这样可以更容易避免拼写错误。

编写oracle插入查询，防止插入重复的行

3 个答案: