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xian123 发表于 2016-11-19 06:31:21

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';
 
 

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