PostgreSQL的dump函数有什么作用

本篇内容主要讲解"PostgreSQL的dump函数有什么作用"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"PostgreSQL的dump函数有什么作用"吧!

Oracle提供了dump函数显示字段的十六进制值,PostgreSQL可通过to_hex函数来进行模拟.

Oracle
测试脚本:

TEST-orcl@DESKTOP-V430TU3>CREATE TABLE t_dumpdemo(description varchar(200));Table created.TEST-orcl@DESKTOP-V430TU3>TEST-orcl@DESKTOP-V430TU3>INSERT INTO t_dumpdemo VALUES('中文');1 row created.TEST-orcl@DESKTOP-V430TU3>INSERT INTO t_dumpdemo VALUES('ABCDE');1 row created.TEST-orcl@DESKTOP-V430TU3>TEST-orcl@DESKTOP-V430TU3>SELECT * FROM t_dumpdemo;DESCRIPTION--------------------------------------------------------------------------------中文ABCDE

dump十六进制值

TEST-orcl@DESKTOP-V430TU3>select dump(description,1016) from t_dumpdemo;DUMP(DESCRIPTION,1016)--------------------------------------------------------------------------------Typ=1 Len=4 CharacterSet=ZHS16GBK: d6,d0,ce,c4Typ=1 Len=5 CharacterSet=ZHS16GBK: 41,42,43,44,45

数据库是用GBK编码,因此'中文'字符编码为GBK编码.

PG
创建dump函数

[local]:5432 pg12@testdb=# CREATE OR REPLACE FUNCTION dump(anynonarray) RETURNS TEXTpg12@testdb-# LANGUAGE plpgsqlpg12@testdb-# ASpg12@testdb-# $function$pg12@testdb$# DECLARE pg12@testdb$#   v_hexstr TEXT;pg12@testdb$#   v_hexbyte TEXT;pg12@testdb$#   v_tmp TEXT;pg12@testdb$#   i INT;pg12@testdb$#   v_len INT;pg12@testdb$# BEGINpg12@testdb$#   SELECT octet_length($1) into v_len;pg12@testdb$#   v_hexstr := 'Len=' || v_len || ' ';pg12@testdb$#   v_tmp := ',';pg12@testdb$#   FOR i in 1..v_len LOOPpg12@testdb$#     select to_hex(get_byte($1::bytea, i-1)) into v_hexbyte;pg12@testdb$#     if i = v_len thenpg12@testdb$#       v_tmp := '';pg12@testdb$#     end if;pg12@testdb$#     v_hexstr := v_hexstr || v_hexbyte || v_tmp;pg12@testdb$#   END LOOP;pg12@testdb$#   -- SELECT encode($1::bytea,'hex') into v_hexbyte;pg12@testdb$#   -- v_hexstr := v_hexstr||','||v_hexbyte;pg12@testdb$#   RETURN v_hexstr;pg12@testdb$# END;pg12@testdb$# $function$;CREATE FUNCTIONTime: 3.621 ms

执行dump函数,显示十六进制值

[local]:5432 pg12@testdb=# select dump(description) from t_dumpdemo;          dump           ------------------------- Len=6 e4,b8,ad,e6,96,87 Len=5 41,42,43,44,45(2 rows)Time: 1.337 ms

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