postgresql SQL语句变量的使用说明

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

cat hank.sql 
select * from tb2 where c2=:name and c3>=:time;

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

 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

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

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)

--定义变量
a numeric;

select sqla into a from table1 where b = '1' ;  --这是sql语句赋值

sql1:= 'select a from table1 where b = ' '1' ' ';
execute sql1 into a; --这是执行存储函数赋值