空字符串:两个单引号,中间无空格等任何内容 在postgresql中,空字符串与null是不同的;而oracle中,空字符串与null等同。测试如下: postgresql中: postgres=# insert into testnull values(1,'feikong'); INSERT 0 1 postgres=# insert into testnull values(2,null); INSERT 0 1 postgres=# insert into testnull values(3,''); INSERT 0 1 postgres=# select * from testnull; id | name ----+--------- 1 | feikong 2 | 3 | (3 rows) postgres=# select * from testnull where name is null; ---只有2为null id | name ----+------ 2 | (1 row) postgres=# select * from testnull where name is not null; id | name ----+--------- 1 | feikong 3 | (2 rows) Oracle中: SQL> insert into testnull values(1,'feikong'); 1 row inserted SQL> insert into testnull values(2,null); 1 row inserted SQL> insert into testnull values(3,''); 1 row inserted SQL> commit; Commit complete SQL> select * from testnull; ID NAME ---------- ---------- 1 feikong 2 3 SQL> select * from testnull where name is null; --2,3为null ID NAME ---------- ---------- 2 3 SQL> select * from testnull where name is not null; ID NAME ---------- ---------- 1 feikong
postgresql与Oracle:空字符串与null
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转载自blog.csdn.net/ghostliming/article/details/73499485
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