no zuo no die系列，来自于pg的wiki。 这一节的内容是：不要使用current_time。 理由是: >1.It returns a value of type timetz, for which see the previous entry. 2.Use whichever of these is appropriate. 原因是： 1.该函数会返回timetz类型，而该类型已废弃（应使用timestamptz）。 2.有更合适的函数可以使用 >CURRENT_TIMESTAMP or now() if you want a timestamp with time zone, LOCALTIMESTAMP if you want a timestamp without time zone, CURRENT_DATE if you want a date, LOCALTIME if you want a time current_time的使用 ``` [local]:5432 pg12@testdb=# select * from pg_proc where proname = 'current_time'; (0 rows) Time: 4.634 ms [local]:5432 pg12@testdb=# \df current_time List of functions Schema | Name | Result data type | Argument data types | Type --------+------+------------------+---------------------+------ (0 rows) Time: 1.083 ms [local]:5432 pg12@testdb=# \d current_time Did not find any relation named "current_time". [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# select * from current_time; current_time -------------------- 11:46:54.895344+08 (1 row) ``` 从pg_proc和psql的df命令找不到该current_time。 相关的替代函数包括 1.CURRENT_TIMESTAMP或者now() 这是带时区的timestamp ``` [local]:5432 pg12@testdb=# \df now List of functions Schema | Name | Result data type | Argument data types | Type ------------+------+--------------------------+---------------------+------ pg_catalog | now | timestamp with time zone | | func (1 row) [local]:5432 pg12@testdb=# select * from pg_proc where proname = 'now'; -[ RECORD 1 ]---+----- oid | 1299 proname | now pronamespace | 11 proowner | 10 prolang | 12 procost | 1 prorows | 0 provariadic | 0 prosupport | - prokind | f prosecdef | f proleakproof | f proisstrict | t proretset | f provolatile | s proparallel | s pronargs | 0 pronargdefaults | 0 prorettype | 1184 proargtypes | proallargtypes | proargmodes | proargnames | proargdefaults | protrftypes | prosrc | now probin | proconfig | proacl | Time: 4.780 ms [local]:5432 pg12@testdb=# select now(); now ------------------------------- 2019-10-21 11:51:40.708556+08 (1 row) Time: 1.860 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# \df current_timestamp List of functions Schema | Name | Result data type | Argument data types | Type --------+------+------------------+---------------------+------ (0 rows) [local]:5432 pg12@testdb=# select * from pg_proc where proname = 'current_timestamp'; (0 rows) Time: 3.014 ms [local]:5432 pg12@testdb=# select * from current_timestamp; current_timestamp ------------------------------ 2019-10-21 11:52:34.31964+08 (1 row) Time: 2.246 ms [local]:5432 pg12@testdb=# select current_timestamp; current_timestamp ------------------------------- 2019-10-21 11:52:37.363806+08 (1 row) Time: 1.827 ms [local]:5432 pg12@testdb=# ``` 2.LOCALTIMESTAMP 这是不带时区的timestamp ``` [local]:5432 pg12@testdb=# \df localtimestamp List of functions Schema | Name | Result data type | Argument data types | Type --------+------+------------------+---------------------+------ (0 rows) [local]:5432 pg12@testdb=# select localtimestamp; localtimestamp ---------------------------- 2019-10-21 11:53:43.376968 (1 row) Time: 1.821 ms [local]:5432 pg12@testdb=# ``` 3.CURRENT_DATE 返回当前日期（年月日） ``` [local]:5432 pg12@testdb=# \df current_date List of functions Schema | Name | Result data type | Argument data types | Type --------+------+------------------+---------------------+------ (0 rows) [local]:5432 pg12@testdb=# select current_date; current_date -------------- 2019-10-21 (1 row) Time: 1.871 ms [local]:5432 pg12@testdb=# ``` 4.LOCALTIME 不带时区的当前时间（时分秒微秒） ``` [local]:5432 pg12@testdb=# \df localtime List of functions Schema | Name | Result data type | Argument data types | Type --------+------+------------------+---------------------+------ (0 rows) [local]:5432 pg12@testdb=# select localtime; localtime ---------------- 11:54:45.38508 (1 row) Time: 2.081 ms [local]:5432 pg12@testdb=# ``` **参考资料** [Don't Do This](https://wiki.postgresql.org/wiki/Don't_Do_This)