postgresql基础

 

 

• OVERLAPS  

SELECT (DATE '2001-02-16', DATE '2001-12-21') OVERLAPS  (DATE '2001-10-30', DATE '2002-10-30');

 

 

 

• 类型转换

REAL '1.23' -- 字串风格
'1.23'::REAL -- PostgreSQL （历史原因）风格

 

type 'string'
'string'::type
CAST ( 'string' AS type )

  eg:

SELECT CAST ('1.11' AS REAL)

    

 

• 字符串常量

$$Dianne's horse$$
$SomeTag$Dianne's horse$SomeTag$

SELECT 'foo'
'bar';

 --等效于

SELECT 'foobar';