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postgresql SQL语句变量的使用说明

发布时间:2021-06-17 22:11:40 所属栏目:经验 来源:互联网
导读: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 SQ

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

2.set使用变量

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

3.通过定义参数实现

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:

1select 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

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