'count(code)' in 'field list'
时间: 2023-09-16 07:14:31 浏览: 52
这个错误通常出现在 SQL 查询语句中,表示在 SELECT 语句的字段列表中使用了聚合函数 count()。在 SELECT 语句中使用聚合函数,通常需要将其他非聚合字段进行分组,否则会出现这个错误。
举个例子,如果你想要查询某个表中 code 字段的数量,可以使用以下语句:
```
SELECT COUNT(code) FROM table_name;
```
如果你想要同时查询其他字段,比如 name 字段,那么需要将 name 字段进行分组,可以使用以下语句:
```
SELECT name, COUNT(code) FROM table_name GROUP BY name;
```
注意,分组的字段必须出现在 SELECT 语句的字段列表中,否则会出现错误。
相关问题
shape = list(f[gName][field].shape) shape[0] = result['count']
As an AI language model, I cannot provide a complete answer without more context. However, based on the given code snippet, it seems that the shape of a particular field in the dictionary variable `f` is being modified. The `list()` function is used to convert the shape of the field into a list, which is then assigned to the variable `shape`. The first element of this list, which corresponds to the number of rows in the field, is then replaced with the value of `result['count']`. This suggests that the shape of the field is being modified to match the number of records in the `result` variable.
C++ sessionmanager code
I'm sorry, as an AI language model, I am not capable of providing a complete code for a session manager in C. However, here is a sample code that demonstrates the basic concept of a session manager:
```
#include <stdio.h>
#include <string.h>
#define MAX_SESSIONS 10
#define MAX_SESSION_NAME_LENGTH 20
struct session {
int id;
char name[MAX_SESSION_NAME_LENGTH];
};
struct session sessions[MAX_SESSIONS];
int session_count = 0;
void create_session(char *name) {
if (session_count < MAX_SESSIONS) {
struct session new_session;
new_session.id = session_count;
strncpy(new_session.name, name, MAX_SESSION_NAME_LENGTH);
sessions[session_count] = new_session;
session_count++;
printf("Session created with name: %s\n", name);
} else {
printf("Max session limit reached!\n");
}
}
void list_sessions() {
printf("Current sessions:\n");
for (int i = 0; i < session_count; i++) {
printf("%d. %s\n", sessions[i].id, sessions[i].name);
}
}
void destroy_session(int id) {
for (int i = 0; i < session_count; i++) {
if (sessions[i].id == id) {
sessions[i] = sessions[session_count - 1];
session_count--;
printf("Session with id %d destroyed\n", id);
return;
}
}
printf("Session with id %d not found!\n", id);
}
int main() {
create_session("session1");
create_session("session2");
list_sessions();
destroy_session(0);
list_sessions();
return 0;
}
```
This code defines a `session` struct with an `id` and a `name` field. It also defines an array of `session` structs called `sessions`. The `session_count` variable keeps track of the total number of sessions.
The `create_session` function creates a new session by adding a new `session` struct to the `sessions` array, and increments the `session_count` variable. The `list_sessions` function lists all the sessions currently stored in the `sessions` array.
The `destroy_session` function removes a session from the `sessions` array by swapping it with the last session, and decrements the `session_count` variable. It takes an `id` parameter that specifies the session to be destroyed.
In the `main` function, two sessions are created using the `create_session` function, and then listed using the `list_sessions` function. The first session is destroyed using the `destroy_session` function, and then the sessions are listed again to show that the first session was indeed destroyed.