Question

可以将以下查询合并到一个查询中吗？

1

public function create($station_id)

2

select a.usr_id, a.usr_desc as ,a.usr_type,b.usr_desc as usr_prof_name 
from sc_usr_prof_m a, sc_usr_type_m b 
where a.usr_type=b.usr_type 
and a.current_status='A' 
order by a.usr_id;

3

select distinct a.usr_id,a.usr_desc,b.dept_name 
from sc_usr_prof_m a ,sc_user_depts b 
where a.usr_id=b.usr_id 
and a.usr_status='E'  
and a.current_status='A';

4

select a.usr_id,a.usr_desc,b.curr_code,b.min_amt,b.max_amt 
from sc_usr_prof_m a, sc_auth_limit_m b  
where a.usr_id=b.usr_id 
and a.usr_status='E'
and a.current_status='A' 
and b.max_amt not in ('0') 
order by b.usr_id;

Answer 1

在不知道你的桌子结构的情况下，很难准确地说出哪种方式能给你带来最好的结果。你可以将查询重写为一个，将各个表连接在一起，但似乎有很多不同的表选择。如果不知道你的桌子设计，就很难说这是否是最好的行动方案。

或者，如果您只是想将结果集合并到一个数据集中，基本上将每个查询的结果合并为一个输出，那么您可以使用UNION [ALL]。您需要确保每个查询的选择列表中的列正确匹配/对齐。这不是理想的，但应该给你你想要的东西。

with combined_results as (
    select a.usr_id as usr_id, 
        a.usr_desc as usr_desc, 
        a.usr_type as usr_type, 
        b.usr_desc as usr_prof_name,
        null as dept_name, 
        null as cur_code,
        0 as min_amt,
        0 as max_amt,
        null as msg_type
    from sc_usr_prof_m a, sc_usr_type_m b 
    where a.usr_type=b.usr_type 
    and a.current_status='A' 
    union all
    select distinct 
        a.usr_id as usr_id, 
        a.usr_desc as usr_desc,
        null as usr_type,
        null as usr_prof_name, 
        b.dept_name as dept_name, 
        null as cur_code,
        0 as min_amt,
        0 as max_amt,
        null as msg_type
    from sc_usr_prof_m a ,sc_user_depts b 
    where a.usr_id=b.usr_id 
    and a.usr_status='E'  
    and a.current_status='A'
    union all
    select a.usr_id as usr_id, 
        a.usr_desc as usr_desc, 
        null as usr_type,
        null as usr_prof_name, 
        null as dept_name,
        b.curr_code as curr_code, 
        b.min_amt as min_amt, 
        b.max_amt as max_amt,
        null as msg_type
    from sc_usr_prof_m a, sc_auth_limit_m b  
    where a.usr_id=b.usr_id 
    and a.usr_status='E'
    and a.current_status='A' 
    and b.max_amt not in ('0') 
    union all
    select a.usr_id as usr_id, 
        a.usr_desc as usr_desc, 
        null as usr_type,
        null as usr_prof_name, 
        null as dept_name,
        null as cur_code,
        0 as min_amt,
        0 as max_amt,
        b.msg_type as msg_type 
    from sc_usr_prof_m a, sc_user_msgs_m b  
    where a.usr_id=b.usr_id 
    and a.usr_status='E' 
    and a.current_status='A' 
    and b.swift_enable='Y'
)
select *
from combined_results 
order by usr_id;

我还建议你写出你的联接：

select a.col1, a.col2, b.col3, b.col4
from my_a_table a
join my_b_table b
on b.col1 = a.col1
where a.col1 = 123;

而不是您目前的表现如何：

select a.col1, a.col2, b.col3, b.col4
from my_a_table a, my_b_table b
where b.col1 = a.col1
and a.col1 = 123;

如果没有其他原因而不是可读性，尤其是在具有多个连接的较大查询中。

将以下查询作为一个查询加入是否可行

1 个答案: