bit_shift_left
description
syntax
BIT_SHIFT_LEFT(BIGINT x, TINYINT c)
将 BIGINT 类型的 x 向左移动 c 位，并将结果作为 BIGINT 返回。 如果 c 小于 0，则返回零。
example
select 8 as x, number as c, bit_shift_left(8, number) as bit_shift_left from numbers("number"="5")
--------------
+------+------+----------------+
| x | c | bit_shift_left |
+------+------+----------------+
| 8 | 0 | 8 |
| 8 | 1 | 16 |
| 8 | 2 | 32 |
| 8 | 3 | 64 |
| 8 | 4 | 128 |
+------+------+----------------+
5 rows in set (0.04 sec)对于 BIGINT 类型的最大值 9223372036854775807（即 BIGINT_MAX），进行一位左移的结果将得到 -2。
WITH tbl AS (
SELECT 9223372036854775807 AS BIGINT_MAX
)
SELECT BIGINT_MAX, bit_shift_left(BIGINT_MAX, 1)
FROM tbl
--------------
+---------------------+-------------------------------+
| BIGINT_MAX | bit_shift_left(BIGINT_MAX, 1) |
+---------------------+-------------------------------+
| 9223372036854775807 | -2 |
+---------------------+-------------------------------+
1 row in set (0.05 sec)keywords
BITSHIFT, BITSHIFTLEFT