VastbaseE100

隐式类型转换

• 定长字符串与数值类型转换

  定长字符串类型CHARACTER与NUMBER/NUMERIC，INT4，INT8，FLOAT4，FLOAT8之间相互转换。

  atlasdb=#  select '1'::CHARACTER =1::number;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=#  select '1'::CHARACTER =1::numeric;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=#  select '1'::CHARACTER =1::int4;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=#  select '1'::CHARACTER =1::int8;
  ?column? 
  ----------
  t
  (1 row)
  
  atlasdb=#  select '1'::CHARACTER =1::float4;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=#  select '1'::CHARACTER =1::float8;
  ?column? 
  ----------
  t
  (1 row)
  

• 变长字符串类型与数值类型转换

  VARCHAR/VARCHAR2与NUMBER/NUMERIC，INT8，FLOAT4，FLOAT8之间相互转换。

  atlasdb=# select '1'::varchar2 =1::NUMERIC;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::varchar2 =1::INT8;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::varchar2 =1::FLOAT4;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::varchar2 =1::FLOAT8;
  ?column? 
  ----------
  t
  (1 row)
  

• 文本类型与数值类型转换

  NUMBER/NUMERIC，INT2，INT4，INT8，FLOAT4，FLOAT8之间相互转换。

  atlasdb=# select '1'::text =1::NUMBER;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::NUMERIC;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::INT2;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::INT4;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::INT8;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::FLOAT4;
  ?column? 
  ----------
  t
  (1 row)
  atlasdb=# select '1'::text =1::FLOAT8;
  ?column? 
  ----------
  t
  (1 row)
  

• 短整型INT2转换为字符串

  INT2转化为CHARACTER，VARCHAR/VARCHAR2。

  atlasdb=# select (1::int2)::varchar2;
  varchar2 
  ----------
  1
  (1 row)
  atlasdb=# select (1::int2)::varchar;
  varchar 
  ---------
  1
  (1 row)
  atlasdb=# select (1::int2)::character;
  bpchar 
  --------
  1
  (1 row)