是否可以动态循环遍历表的列? [英] Is it possible to dynamically loop through a table's columns?

问题描述

我有一个表测试的触发器函数，它具有以下代码片段:

I have a trigger function for a table test which has the following code snippet:

IF TG_OP='UPDATE' THEN
    IF OLD.locked > 0 AND
 (       OLD.org_id <> NEW.org_id OR
            OLD.document_code <> NEW.document_code OR
            -- other columns ...
 )
THEN
    RAISE EXCEPTION 'Message';
-- more code

所以我静态检查所有列的新值及其以前的值以确保完整性.现在每次我的业务逻辑发生变化并且我必须向该表中添加新列时，我每次都必须修改此触发器.我认为如果我能以某种方式动态检查该表的所有列，而无需明确输入它们的名称会更好.

So I am statically checking all the column's new value with its previous value to ensure integrity. Now every time my business logic changes and I have to add new columns into that table, I will have to modify this trigger each time. I thought it would be better if somehow I could dynamically check all the columns of that table, without explicitly typing their name.

怎么做?

推荐答案

看一下information_schema，有一个视图columns".执行查询以从触发触发器的表中获取所有当前列名:

Take a look at the information_schema, there is a view "columns". Execute a query to get all current columnnames from the table that fired the trigger:

SELECT 
    column_name 
FROM 
    information_schema.columns 
WHERE 
    table_schema = TG_TABLE_SCHEMA 
AND 
    table_name = TG_TABLE_NAME;

遍历结果即可！

更多信息可以在详细手册中找到.

More information can be found in the fine manual.

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