时间：2021-09-09 09:52:49 | 栏目：PostgreSQL | 点击：次
一般变量使用我们都是放在函数里面，这里开发需求，要在SQL直接使用变量，方便查找一些问题，比如时间变量，要根据时间进行筛选
这里有三种方法可以实现
表数据如下：
hank=> select * from tb2; c1 | c2 | c3 ----+-------+---------------------------- 1 | hank | 2018-02-06 10:08:00.787503 2 | dazui | 2018-02-06 10:08:08.542481 3 | wahah | 2018-02-06 10:08:15.468527 4 | aaaaa | 2018-02-06 10:18:39.289523
SQL文本如下
cat hank.sql select * from tb2 where c2=:name and c3>=:time;
通过psql查看
psql -v name="'hank'" -v time="'2018-02-06 10:08:00'" -f hank.sql c1 | c2 | c3 ----+------+---------------------------- 1 | hank | 2018-02-06 10:08:00.787503
或者
psql -v name="'hank'" -v time="'2018-02-06 10:08:00'" -c '\i hank.sql' c1 | c2 | c3 ----+------+---------------------------- 1 | hank | 2018-02-06 10:08:00.787503
效果一样
hank=> \set name hank hank=> \set time '2018-02-06 10:09:00' hank=> select * from tb2 where c2=:'name' and c3>=:'time'; c1 | c2 | c3 ----+------+---------------------------- 1 | hank | 2018-02-06 10:08:00.787503
设置一个session级别的参数，通过current_setting取值
hank=> set session "asasd.time" to "2018-02-06 10:09:00";
SET
hank=> select * from tb2 where c3 >= current_setting('asasd.time')::timestamp;
c1 | c2 | c3
----+-------+----------------------------
4 | aaaaa | 2018-02-06 10:18:39.289523
(1 row)
补充：postgresql存储函数/存储过程用sql语句来给变量赋值
--定义变量 a numeric;
方式一：
select sqla into a from table1 where b = '1' ; --这是sql语句赋值
方式二：
sql1:= 'select a from table1 where b = ' '1' ' '; execute sql1 into a; --这是执行存储函数赋值