select p into k
时间: 2024-01-27 15:14:49 浏览: 59
根据提供的引用内容,你可以使用SELECT INTO语句将查询结果赋值给一个变量。下面是一个示例:
```sql
SELECT column_name INTO variable_name FROM table_name WHERE condition;
```
在这个示例中,column_name是要查询的列名,variable_name是要赋值的变量名,table_name是要查询的表名,condition是查询的条件。
请注意,这个语句只能用于查询结果只有一行一列的情况。如果查询结果有多行或多列,将会抛出错误。
相关问题
C++写Bob has a magic computer which has infinite USB ports. But there is a problem with this computer——it can only read and write the two most recently inserted USB disks. Initially, Bob has n USB disks and every USB disk has one unique file. He wants to insert all the n USB disks into his computer. Since his computer is old, he must insert USB disk in the following way: Select 2 unplugged USB disks, insert them into computer. The two USB disks inserted in the previous step will share the files with each other, which means after that both two USB disks will have all files either in the first one or in the second one. If all the n USB disks are in the computer, the task is finished. Otherwise, choose one USB disk in the computer, unplug it and go to step 1 . Bob wants to know the minimum number of n such that there is a sequence of operations that ends up with at least k different files in each USB disk. Input Only one number,k (2≤k≤100000 ),meaning that finally each USB disk owns at least k different files. Output You need to output one number n , which means the minimum number of USB disks in module 998244353.
以下是使用 C++ 解决此问题的代码:
```cpp
#include <iostream>
#include <cstdio>
using namespace std;
const int mod = 998244353;
int k;
int pow_mod(int x, int p) {
int res = 1;
while (p) {
if (p & 1) res = (long long)res * x % mod;
x = (long long)x * x % mod;
p >>= 1;
}
return res;
}
int main() {
scanf("%d", &k);
int ans = 1;
while (ans < k) ans <<= 1;
printf("%d\n", pow_mod(2, ans - 1));
return 0;
}
```
解释:首先将 n 设为 1,然后每次将 n 左移一位(即乘以 2),直到 n 大于等于 k。这样就可以保证最终每个 USB 盘上的文件数都至少为 k。根据题意,只需要算出插入 n 个 USB 盘的方案数,即 C(n, 2)C(n-2, 2)C(n-4, 2)...C(4, 2)C(2, 2),可以化简为 2^(n-1),所以最后的答案为 2^(n-1) % 998244353。
IF LENGTH(tmp_char)>1 THEN SELECT ELT(INTERVAL(CONV(HEX(tmp_char),16,10),0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,0xBBF7,0xBFA6,0xC0AC ,0xC2E8,0xC4C3,0xC5B6,0xC5BE,0xC6DA,0xC8BB,0xC8F6,0xCBFA,0xCDDA ,0xCEF4,0xD1B9,0xD4D1), 'A','B','C','D','E','F','G','H','J','K','L','M','N','O','P','Q','R','S','T','W','X','Y','Z') INTO tmp_cc; 如何转换成postgresql的sql语句
在 PostgreSQL 中,你可以使用 `CASE` 表达式来实现类似的逻辑。下面是将给定的 SQL 代码转换为 PostgreSQL 的 SQL 语句的示例:
```sql
SELECT
CASE
WHEN LENGTH(tmp_char) > 1 THEN
CASE
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 45281 AND 45285 THEN 'A'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 45457 AND 45458 THEN 'B'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 45729 AND 45755 THEN 'C'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 46062 AND 46090 THEN 'D'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 46346 AND 46378 THEN 'E'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 46498 AND 46530 THEN 'F'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 46657 AND 46689 THEN 'G'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 46817 AND 46845 THEN 'H'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 47103 AND 47127 THEN 'J'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 47334 AND 47358 THEN 'K'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 47468 AND 47492 THEN 'L'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 47610 AND 47638 THEN 'M'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 47809 AND 47829 THEN 'N'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48026 AND 48052 THEN 'O'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48162 AND 48187 THEN 'P'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48274 AND 48300 THEN 'Q'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48438 AND 48464 THEN 'R'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48657 AND 48682 THEN 'S'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 48858 AND 48883 THEN 'T'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 49189 AND 49217 THEN 'W'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 49324 AND 49354 THEN 'X'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 49382 AND 49407 THEN 'Y'
WHEN CONV(HEX(tmp_char), 16, 10) BETWEEN 49655 AND 49690 THEN 'Z'
END
END AS tmp_cc;
```
请注意,我已经将 `ELT` 函数替换为了 `CASE` 表达式,并且使用了 `BETWEEN` 来检查给定的范围。你可能需要根据具体的需求对这些范围进行调整。
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