PostgreSQL has no NVL solution. PostgreSQL queries all tables

postgresql No, nvl Solutions for

oracle Of NVL(col,0) Is to judge if col Assign a value when the field is empty 0.
postgresql There are similar methods in COALESCE,
COALESCE The function is the first non - return parameter null Value , It requires at least one of the parameters to be true or false null Of , If the parameters are all null Will report a mistake , as follows

SELECT coalesce(collect_result,0) as collect_result  FROM collect

select COALESCE(null,null); // Report errors 
select COALESCE(null,null,now()::varchar,''); // The result will be the current time 
select COALESCE(null,null,'',now()::varchar); // The results will be ''
// It can cooperate with other functions to realize some complex functions ： Query student's name , If the student's name is null or '' Is displayed “ Name is empty ”
select case when coalesce(name,'') = '' then ' Name is empty ' else name end from student;

postgresql Query all tables

select * from pg_tables where schemaname = ' Schema name ' order by tablename asc;