PostgreSql +布尔类型转换为字符类型

Question

在这里，我无法将布尔值转换为postgre sql查询中的字符。

SELECT *FROM ltl_class_nmfc_aliases 
WHERE ltl_class_nmfc_aliases.id 
NOT IN(SELECT ltl_class_nmfc_aliases_id FROM commodities_shippeds 
WHERE commodities_shipped_obj_type LIKE 'ClientOffice') 
OR ltl_class_id IS NULL 
AND lower(commodity_description_alias) LIKE E'%%' 
AND lower(ltl_value) LIKE E'%92.5%' 
AND hazardous :: integer LIKE E '%%' 
AND cast(schedule_b as character varying(255)) LIKE E'%%' 
AND cast(harmonized_tariff as character varying(255)) LIKE E'%%' 
ORDER BY commodity_description_alias,ltl_value LIMIT 25; 

在这里，我无法在AND hazardous :: integer LIKE E '%%' 到类型转换建议我如何做类型转换？

Answer 1

如何使用case声明？

(case when hazardous then 'Bad juju' else 'Ok.' end) as safety 

您还可以使用cast声明：

postgres=# select cast(1 as boolean); 
bool 
------ 
t 

postgres=# select cast(0 as boolean); 
bool 
------ 
f 

postgres=# select cast('false' as boolean); 
bool 
------ 
f 

postgres=# select cast('False' as boolean); 
bool 
------ 
f 

postgres=# select cast('T' as boolean); 
bool 
------ 
t 

postgres=# select cast('F' as boolean); 
bool 
------ 
f 

postgres=# select cast('Y' as boolean); 
bool 
------ 
t 

postgres=# select cast('N' as boolean); 
bool 
------ 
f 

所以它可能是：

select ... where ... and hazardous = cast(:your_variable as bool) 

您也可以转换为VARCHAR：

select cast(hazardous to varchar)... 

一些数据库驱动程序（比如Borland的BDE）扼杀了这个，因为他们期望varchar字段有明确的列宽。

如果您只是筛选hazardous=true，请仅使用“AND危险”。