Question

我正在尝试比较由update触发器填充的历史记录表中的值，以查看JSON字段的旧值和新值中的某些列是否相等，如果所有列均相等，则可以在查询时创建案例。这是我想要做的：

SQL

create table history
(
    id           serial not null,
    ts           timestamp default now(),
    table_schema text,
    table_name   text,
    operation    text,
    updated_by   text      default CURRENT_USER,
    new          json,
    old          json
);


With t AS (
select id,
       old->>'field1' = new->>'field1' as isMatchField1,
       old->>'field2' = new->>'field2' as isMatchField2,
       old->>'field3' = new->>'field3' as isMatchField3,
       old->>'field4' = new->>'field4' as isMatchField4
from history)

select id, array [isMatchField1, isMatchField2, isMatchField3, isMatchField4] from t

输出

1，{true，true，false，null}

如何从数组中筛选出所有空值，并在查询时进行案例分析以查看是否仅存在真值。基本上我想做类似的事情：

select id, 
case when array field is only true and null then 'no changes made'
else
  'changes made'
end as updated
from t

在PostgreSQL中，如何仅对数组列进行过滤和搜索以获取唯一值？

0 个答案: