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发布时间:2022-04-07 16:21
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时间:2022-04-07 20:43
执行SQL语句
int mysql_query(MYSQL *pmysql,const char *sql);
参数pmysql是连接到MySQL的指针。 参数sql是要执行的SQL语句。 成功返回0,失败返回非0。 插入数据例子int main(int arg, char *args[]) { MYSQL *connection, mysql; mysql_init(&mysql); connection = mysql_real_connect(&mysql, "localhost", "dbuser", "dbuser", "db1",0,0,0); if (connect == NULL) { printf(mysql_error(&mysql)); return EXIT_FAILURE; } int state = mysql_query(connection, "INSERT INTO table1 (NAME,SEX,AGE,CLASS) VALUES (‘HAHA‘,1,30,‘666‘)"); if (state != 0) { printf(mysql_error(connection)); return EXIT_FAILURE; } mysql_close(connection); return EXIT_SUCCESS; }
修改数据例子
int main(int arg, char *args[]) { MYSQL *connection, mysql; mysql_init(&mysql); connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0); if (connect == NULL) { printf(mysql_error(&mysql)); return EXIT_FAILURE; } int state = mysql_query(connection, "UPDATE table1 SET CLASS = ‘250‘ WHERE NAME = ‘HAHA‘"); if (state != 0) { printf(mysql_error(connection)); return EXIT_FAILURE; } mysql_close(connection); return EXIT_SUCCESS; }
删除数据例子
int main(int arg, char *args[]) { MYSQL *connection, mysql; mysql_init(&mysql); connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0); if (connect == NULL) { printf(mysql_error(&mysql)); return EXIT_FAILURE; } int state = mysql_query(connection, “DELETE FROM table1 WHERE NAME = ‘HAHA‘"); if (state != 0) { printf(mysql_error(connection)); return EXIT_FAILURE; } mysql_close(connection); return EXIT_SUCCESS; }
执行SELECT语句得到查询结果
MYSQL_RES *mysql_store_result(MYSQL *pmysql);
成功返回一个查询结果指针,查询无结果或者错误返回NULL。mysql_free_result(MYSQL_RES *res)
调用完mysql_store_result,一定要用mysql_free_result释放相关的资源。 查看查询结果MYSQL_ROW mysql_fetch_row(MYSQL_RES *result);
例子while(row = mysql_fetch_row(result)) != NULL)
{
printf(“name:%s,sex:%s,age:%s,class:%s ”,row[0], row[1], row[2],row[3]
}
尽管在表中age是数字,但mysql返回的只不过是以NULL结尾的字符串。 查看查询结果中的字段信息MYSQL_FIELD *mysql_fetch_field (MYSQL_RES *result);
例子while ((sqlField = mysql_fetch_field(result)) != NULL)
{
printf("%s ", sqlField->name);
}
执行SELECT例子1
int main(int arg, char *args[]) { MYSQL *connection, mysql; mysql_init(&mysql); connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0); if (connect == NULL) { printf(mysql_error(&mysql)); return EXIT_FAILURE; } int state = mysql_query(connection, "SELECT NAME,SEX,AGE,CLASS FROM table1"); if (state != 0) { printf(mysql_error(connection)); return EXIT_FAILURE; } MYSQL_RES *result = mysql_store_result(connection); if (result == (MYSQL_RES *)NULL) { printf(mysql_error(connection)); return EXIT_FAILURE; } MYSQL_ROW row; while((row = mysql_fetch_row(result)) != NULL) { printf("name %s, sex %s, age %s, class %s ", row[0],row[1],row[2],row[3]); } mysql_free_result(result); mysql_close(connection); return EXIT_SUCCESS; }
执行SELECT例子2
int main(int arg, char *args[]) { if (arg < 5) return 0; MYSQL *connection, mysql; mysql_init(&mysql); connection = mysql_real_connect(&mysql, args[1], args[2], args[3], args[4], 0, 0, 0); if (connection == NULL) { printf("%s ", mysql_error(&mysql)); return EXIT_FAILURE; } printf("success connect to mysql "); int state = mysql_query(connection, "SET NAMES utf8"); char buf[1024]; while (1) { memset(buf, 0, sizeof(buf)); read(STDIN_FILENO, buf, sizeof(buf)); if (strncmp(buf, "exit", 4) == 0) { break; } state = mysql_query(connection, buf); if (state != 0) { printf("%s ", mysql_error(connection)); } MYSQL_RES *result = mysql_store_result(connection); if (result == NULL) { printf("%s ", mysql_error(connection)); break; } MYSQL_FIELD *sqlField; int iFieldCount = 0; while ((sqlField = mysql_fetch_field(result)) != NULL) { printf("%s ", sqlField->name); iFieldCount++; } printf(" "); MYSQL_ROW row; while ((row = mysql_fetch_row(result)) != NULL) { int i; for (i = 0; i < iFieldCount; i++) { printf("%s ", row[i]); } printf(" "); } mysql_free_result(result); } mysql_close(connection); return EXIT_SUCCESS; }
断开连接
mysql_close(MYSQL *connect);
使用完数据库后要记得断开连接,释放相关资源。 复制去Google翻译翻译结果数据库编程
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时间:2022-04-07 17:51