Question

如果未使用EXISTS引入子查询，则只能在选择list.error中指定一个表达式。不知道怎么做if exists语句。

SELECT DISTINCT
t1.id,t1.scn,t1.vsl_name,case when t1.id = t1.id  THEN 'IMPORT' ELSE '0' END AS import_export,
dbo.fn_format_datetime(t1.act_arr_dt_tm) AS act_arr_dt_tm,
dbo.fn_format_datetime(t1.act_dept_dt_tm) AS act_dept_dt_tm,
(       SELECT t1.scn, COUNT(t1.id) AS total_count_bl_status_c
        FROM ccosbl t1
        INNER JOIN vesvoy t2 ON t2.scn= t1.scn
        WHERE t1.status_ind= 'C'
        GROUP BY t1.scn)
FROM vesvoy t1
INNER JOIN ccosbl t2 ON t2.scn = t1.scn
WHERE t2.status_ind = 'C'
GROUP BY t1.scn,t1.vsl_name,t1.act_arr_dt_tm,t1.act_dept_dt_tm,t1.id

我需要将select语句合二为一。在sql中还有其他方法吗？

Answer 1

如果您坚持使用相关子查询，那么您需要确保选择中只包含一列：

SELECT DISTINCT
t1.id,t1.scn,t1.vsl_name,case when t1.id = t1.id  THEN 'IMPORT' ELSE '0' END AS import_export,
dbo.fn_format_datetime(t1.act_arr_dt_tm) AS act_arr_dt_tm,
dbo.fn_format_datetime(t1.act_dept_dt_tm) AS act_dept_dt_tm,
(       SELECT COUNT(t4.id) AS total_count_bl_status_c
        FROM ccosbl t4
        INNER JOIN vesvoy t5 ON t4.scn= t5.scn
        WHERE t1.status_ind= 'C' and t4.scn = t2.scn)
FROM vesvoy t1
INNER JOIN ccosbl t2 ON t2.scn = t1.scn
WHERE t2.status_ind = 'C'
GROUP BY t1.scn,t1.vsl_name,t1.act_arr_dt_tm,t1.act_dept_dt_tm,t1.id

但是，更好的方法是使用带有连接的子查询：

SELECT DISTINCT
t1.id,t1.scn,t1.vsl_name,case when t1.id = t1.id  THEN 'IMPORT' ELSE '0' END AS import_export,
dbo.fn_format_datetime(t1.act_arr_dt_tm) AS act_arr_dt_tm,
dbo.fn_format_datetime(t1.act_dept_dt_tm) AS act_dept_dt_tm,
t3.total_count_bl_status_c
FROM vesvoy t1
INNER JOIN ccosbl t2 ON t2.scn = t1.scn
LEFT JOIN
(       SELECT t4.scn, COUNT(t4.id) AS total_count_bl_status_c
        FROM ccosbl t4
        INNER JOIN vesvoy t5 ON t4.scn= t5.scn
        WHERE t4.status_ind= 'C'
        GROUP BY t4.scn) t3
ON t2.scn = t3.scn
WHERE t2.status_ind = 'C'
GROUP BY t1.scn,t1.vsl_name,t1.act_arr_dt_tm,t1.act_dept_dt_tm,t1.id

Answer 2

试试这个：

SELECT t3.id t3.scn,total_count_bl_status_c,act_arr_dt_tm,act_dept_dt_tm,vsl_name,case when t3.id = t3.id  THEN 'IMPORT' ELSE '0' END AS import_export,
dbo.fn_format_datetime(t3.act_arr_dt_tm) AS act_arr_dt_tm,
dbo.fn_format_datetime(t3.act_dept_dt_tm) AS act_dept_dt_tm from
(SELECT t2.scn, COUNT(t2.id) AS total_count_bl_status_c
        FROM ccosbl t1
        INNER JOIN 
        vesvoy t2 
        ON t2.scn= t1.scn
        WHERE t1.status_ind= 'C'
        GROUP BY t1.scn)as t3
inner join 

(SELECT * from ccosbl) as t4 on 
ON t4.scn = t3.scn

如果存在sql错误，则组合2选择语句

2 个答案: