这篇文章主要讲解了“怎么使用PostgreSQL中的COPY命令”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“怎么使用PostgreSQL中的COPY命令”吧！
Copy命令在PG 12有所增强,在COPY FROM时可添加WHERE条件过滤.
PG 11
Copy命令
testdb=# \help copy
Command: COPY
Description: copy data between a file and a table
Syntax:
COPY table_name [ ( column_name [, ...] ) ]
FROM { 'filename' | PROGRAM 'command' | STDIN }
[ [ WITH ] ( option [, ...] ) ]
COPY { table_name [ ( column_name [, ...] ) ] | ( query ) }
TO { 'filename' | PROGRAM 'command' | STDOUT }
[ [ WITH ] ( option [, ...] ) ]
where option can be one of:
FORMAT format_name
OIDS [ boolean ]
FREEZE [ boolean ]
DELIMITER 'delimiter_character'
NULL 'null_string'
HEADER [ boolean ]
QUOTE 'quote_character'
ESCAPE 'escape_character'
FORCE_QUOTE { ( column_name [, ...] ) | * }
FORCE_NOT_NULL ( column_name [, ...] )
FORCE_NULL ( column_name [, ...] )
ENCODING 'encoding_name'简单使用
testdb=# drop table if exists t_copy; DROP TABLE testdb=# CREATE TABLE t_copy(id int,c1 varchar(20)); CREATE TABLE testdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x; INSERT 0 1000 testdb=# testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 testdb=# drop table if exists t_import; DROP TABLE testdb=# CREATE TABLE t_import(id int,c1 varchar(20)); CREATE TABLE testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 testdb=# select * from t_import limit 10; id | c1 ----+------- 1 | c1-1 2 | c1-2 3 | c1-3 4 | c1-4 5 | c1-5 6 | c1-6 7 | c1-7 8 | c1-8 9 | c1-9 10 | c1-10 (10 rows)
不支持WHERE条件过滤
testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|' where id < 5; ERROR: syntax error at or near "where" LINE 1: ...t FROM '/tmp/data/t_copy.txt' with DELIMITER '|' where id <...
PG 12
COPY命令语法
[local]:5432 pg12@testdb=# \help copy
Command: COPY
Description: copy data between a file and a table
Syntax:
COPY table_name [ ( column_name [, ...] ) ]
FROM { 'filename' | PROGRAM 'command' | STDIN }
[ [ WITH ] ( option [, ...] ) ]
[ WHERE condition ]
COPY { table_name [ ( column_name [, ...] ) ] | ( query ) }
TO { 'filename' | PROGRAM 'command' | STDOUT }
[ [ WITH ] ( option [, ...] ) ]
where option can be one of:
FORMAT format_name
FREEZE [ boolean ]
DELIMITER 'delimiter_character'
NULL 'null_string'
HEADER [ boolean ]
QUOTE 'quote_character'
ESCAPE 'escape_character'
FORCE_QUOTE { ( column_name [, ...] ) | * }
FORCE_NOT_NULL ( column_name [, ...] )
FORCE_NULL ( column_name [, ...] )
ENCODING 'encoding_name'
URL: https://www.postgresql.org/docs/12/sql-copy.html支持WHERE条件过滤
[local]:5432 pg12@testdb=# drop table if exists t_copy; DROP TABLE Time: 50.327 ms [local]:5432 pg12@testdb=# CREATE TABLE t_copy(id int,c1 varchar(20)); CREATE TABLE Time: 5.038 ms [local]:5432 pg12@testdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x; INSERT 0 1000 Time: 16.422 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 Time: 4.795 ms [local]:5432 pg12@testdb=# drop table if exists t_import; DROP TABLE Time: 4.798 ms [local]:5432 pg12@testdb=# CREATE TABLE t_import(id int,c1 varchar(20)); CREATE TABLE Time: 2.462 ms [local]:5432 pg12@testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|' WHERE id < 5; COPY 4 Time: 4.842 ms [local]:5432 pg12@testdb=# select * from t_import; id | c1 ----+------ 1 | c1-1 2 | c1-2 3 | c1-3 4 | c1-4 (4 rows) Time: 6.103 ms
感谢各位的阅读，以上就是“怎么使用PostgreSQL中的COPY命令”的内容了，经过本文的学习后，相信大家对怎么使用PostgreSQL中的COPY命令这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是创新互联，小编将为大家推送更多相关知识点的文章，欢迎关注！
