参数没有从 Postgres function 中获取值

Question

I have a simple Postgres function where I want to take table_name as a parameter and pass it into an argument and delete the data from table by condition.

CREATE OR REPLACE FUNCTION cdc.audit_refresh(tablename text)
RETURNS integer AS
$$
BEGIN
   delete from tablename where id<4;
   RETURN(select 1);
END;
$$ LANGUAGE plpgsql;

select cdc.audit_refresh('cdc.adf_test');

But it throws out an error that tablename ERROR: relation "tablename" does not exist in the delete statement.(refer snapshot)

Answer 1

What you want to achieve is to execute Dynamic SQL statements. You can do this with EXECUTE . See more here

CREATE OR REPLACE FUNCTION audit_refresh(tablename text)
    RETURNS integer AS
$$
DECLARE
    stmt TEXT;
BEGIN
    stmt = 'delete from '||tablename||' where id<4;';
    EXECUTE stmt;
    RETURN 1;
END
$$ LANGUAGE plpgsql;