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PostgreSql bit varying

PostgreSql bit varying

2023年02月15日我永远爱学习

PostgreSql bit varying

应用场景

存储和可视化位掩码

参考

是动态长度的bit，以可读二进制数的方式展示

1	`SELECT B'10001' as num；`

num
10001

运算

&位与运算
|位或运算
#异或运算
~非运算
<<位左移
>>位右移
||位拼接

SELECT
    B'10001' & B'01101' as "and",
    B'10001' | B'01101' as "or",
  B'10001' # B'01101' as "eor ",
  ~B'10001'  as "not",
  B'11111' >> 2  as "shiftL",
  B'11111' << 2  as "shiftR",
    B'101' || B'01' as "cancat ";

and	or	eor	not	shiftL	shiftR	cancat
00001	11101	11100	01110	00111	11100	10101

转换

SELECT 
    B'10001' as "varbit",
  cast(B'10001' as bit(3)) as "bit3",
    cast(B'10001' as bit(5)) as "bit",
    cast(B'10001' as bit(7)) as "bit7",
    cast(cast(B'10001' as bit(5)) as  integer)  as  "int",
    B'10001'::bit(5)::integer as "intLambda";

varbit	bit3	bit	bit7	int	intLambda
10001	100	10001	1000100	17	17

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