sql - 获取 PostgreSQL 查询的执行时间

Question

DECLARE @StartTime datetime,@EndTime datetime

SELECT @StartTime=GETDATE()

select distinct born_on.name
from   born_on,died_on
where (FLOOR(('2012-01-30'-born_on.DOB)/365.25) <= (
    select max(FLOOR((died_on.DOD - born_on.DOB)/365.25))
    from   died_on, born_on
    where (died_on.name=born_on.name))
    )
and   (born_on.name <> All(select name from died_on))

SELECT @EndTime=GETDATE()

SELECT DATEDIFF(ms,@StartTime,@EndTime) AS [Duration in millisecs]

我无法获取查询时间。相反，我收到以下错误:

sql:/home/an/Desktop/dbms/query.sql:9: ERROR:  syntax error at or near "@"
LINE 1: DECLARE @StartTime datetime,@EndTime datetime

Answer 1

如果你的意思是在 psql 中，而不是你正在编写的某个程序，请使用 \? 寻求帮助，并查看:

\timing [on|off]       toggle timing of commands (currently off)

然后你得到如下输出:

# \timing on
Timing is on.

# select 1234;        
 ?column? 
----------
     1234
(1 row)

Time: 0.203 ms