【手写数据库内核miniToadb】第1天模拟数据库流程，分析数据库内核的组成 - ToB企服应用市场:ToB评测及商务社交产业平台

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_FIELDS 10
#define MAX_FIELD_LEN 20
#define MAX_RECORDS 100
struct field
{
char name[MAX_FIELD_LEN];
char type[MAX_FIELD_LEN];
};
struct record
{
int id;
char fields[MAX_FIELDS][MAX_FIELD_LEN];
};
struct table
{
char name[MAX_FIELD_LEN];
struct field fields[MAX_FIELDS];
int num_fields;
struct record records[MAX_RECORDS];
int num_records;
};

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int main()
{
struct table t;
create_table(&t);
while (1)
{
printf("Enter command (insert/select/update/delete/exit): ");
char command[MAX_FIELD_LEN];
scanf("%s", command);
if (strcmp(command, "insert") == 0)
{
insert_record(&t);
} else if (strcmp(command, "select") == 0)
{
print_table(&t);
} else if (strcmp(command, "update") == 0)
{
update_record(&t);
} else if (strcmp(command, "delete") == 0)
{
delete_record(&t);
} else if (strcmp(command, "exit") == 0)
{
break;
} else
{
printf("Invalid command\n");
}
}
return 0;
}

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void create_table(struct table *t)
{
printf("Enter table name: ");
scanf("%s", t->name);
printf("Enter number of fields: ");
scanf("%d", &t->num_fields);
printf("Enter field names and types:\n");
for (int i = 0; i < t->num_fields; i++)
{
printf("Field %d name: ", i+1);
scanf("%s", t->fields[i].name);
printf("Field %d type: ", i+1);
scanf("%s", t->fields[i].type);
}
}
void insert_record(struct table *t)
{
if (t->num_records >= MAX_RECORDS)
{
printf("Table is full\n");
return;
}
t->records[t->num_records].id = t->num_records + 1;
printf("Enter field values:\n");
for (int i = 0; i < t->num_fields; i++)
{
printf("%s: ", t->fields[i].name);
scanf("%s", t->records[t->num_records].fields[i]);
}
t->num_records++;
}
void print_table(struct table *t)
{
printf("%s:\n\t", t->name);
for (int i = 0; i < t->num_fields; i++)
{
printf("%s\t", t->fields[i].name);
}
printf("\n");
for (int i = 0; i < t->num_records; i++)
{
printf("%d\t", t->records[i].id);
for (int j = 0; j < t->num_fields; j++)
{
printf("%s\t", t->records[i].fields[j]);
}
printf("\n");
}
}
void update_record(struct table *t)
{
int id;
printf("Enter record id: ");
scanf("%d", &id);
if (id < 1 || id > t->num_records)
{
printf("Invalid id\n");
return;
}
printf("Enter field values:\n");
for (int i = 0; i < t->num_fields; i++)
{
printf("%s: ", t->fields[i].name);
scanf("%s", t->records[id-1].fields[i]);
}
}
void delete_record(struct table *t)
{
int id;
printf("Enter record id: ");
scanf("%d", &id);
if (id < 1 || id > t->num_records)
{
printf("Invalid id\n");
return;
}
for (int i = id-1; i < t->num_records-1; i++)
{
t->records[i] = t->records[i+1];
}
t->num_records--;
}

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[senllang@hatch exam_01]$ gcc demo_1.c -o demo
[senllang@hatch exam_01]$ ./demo
Enter table name: student
Enter number of fields: 2
Enter field names and types:
Field 1 name: sid
Field 1 type: int
Field 2 name: sname
Field 2 type: varchar
Enter command (insert/select/update/delete/exit): insert
Enter field values:
sid: 100
sname: liqiang
Enter command (insert/select/update/delete/exit): insert
Enter field values:
sid: 101
sname: liuye
Enter command (insert/select/update/delete/exit): select
student:
sid sname
1 100 liqiang
2 101 liuye
Enter command (insert/select/update/delete/exit): update
Enter record id: 2
Enter field values:
sid: 101
sname: liuyewen
Enter command (insert/select/update/delete/exit): select
student:
sid sname
1 100 liqiang
2 101 liuyewen
Enter command (insert/select/update/delete/exit): exit

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