MYSQL C API : mysql_real_query()
1 enum enum_field_types { 2 MYSQL_TYPE_DECIMAL, 3 MYSQL_TYPE_TINY, 4 MYSQL_TYPE_SHORT, 5 MYSQL_TYPE_LONG, 6 MYSQL_TYPE_FLOAT, 7 MYSQL_TYPE_DOUBLE, 8 MYSQL_TYPE_NULL, 9 MYSQL_TYPE_TIMESTAMP, 10 MYSQL_TYPE_LONGLONG, 11 MYSQL_TYPE_INT24, 12 MYSQL_TYPE_DATE, 13 MYSQL_TYPE_TIME, 14 MYSQL_TYPE_DATETIME, 15 MYSQL_TYPE_YEAR, 16 MYSQL_TYPE_NEWDATE, 17 MYSQL_TYPE_VARCHAR, 18 MYSQL_TYPE_BIT, 19 MYSQL_TYPE_TIMESTAMP2, 20 MYSQL_TYPE_DATETIME2, 21 MYSQL_TYPE_TIME2, 22 MYSQL_TYPE_NEWDECIMAL=246, 23 MYSQL_TYPE_ENUM=247, 24 MYSQL_TYPE_SET=248, 25 MYSQL_TYPE_TINY_BLOB=249, 26 MYSQL_TYPE_MEDIUM_BLOB=250, 27 MYSQL_TYPE_LONG_BLOB=251, 28 MYSQL_TYPE_BLOB=252, 29 MYSQL_TYPE_VAR_STRING=253, 30 MYSQL_TYPE_STRING=254, 31 MYSQL_TYPE_GEOMETRY=255 32 } 33 34 typedef struct st_mysql_field { 35 char *name; /* Name of column 列名 */ 36 char *org_name; /* Original column name, if an alias */ 37 char *table; /* Table of column if column was a field */ 38 char *org_table; /* Org table name, if table was an alias */ 39 char *db; /* Database for table */ 40 char *catalog; /* Catalog for table */ 41 char *def; /* Default value (set by mysql_list_fields) */ 42 unsigned long length; /* Width of column (create length) */ 43 unsigned long max_length; /* Max width for selected set */ 44 unsigned int name_length; 45 unsigned int org_name_length; 46 unsigned int table_length; 47 unsigned int org_table_length; 48 unsigned int db_length; 49 unsigned int catalog_length; 50 unsigned int def_length; 51 unsigned int flags; /* Div flags */ 52 unsigned int decimals; /* Number of decimals in field */ 53 unsigned int charsetnr; /* Character set */ 54 enum enum_field_types type; /* Type of field. See mysql_com.h for types */ // 字段的mysql 数据类型 55 void *extension; 56 } MYSQL_FIELD; 57 58 59 int mysql_real_query(MYSQL *mysql, const char *q, unsigned long length); 60 说明：执行SQL 61 参数1：已初始化的MYSQL 实例； 62 参数2：SQL 语句； 63 参数3：SQL 语句字符数。 64 65 MYSQL_RES *mysql_store_result(MYSQL *mysql); 66 说明：对于成功检索了数据的每个查询（SELECT、SHOW、DESCRIBE、EXPLAIN、CHECK TABLE等），必须调用mysql_store_result()或mysql_use_result() 67 参数：已初始化的MYSQL 实例。 68 69 // typedef char **MYSQL_ROW; 70 MYSQL_ROW mysql_fetch_row(MYSQL_RES *result); 71 说明：检索一个结果集合的下一行。当在mysql_store_result()之后使用时，如果没有更多的行可检索时，mysql_fetch_row()返回NULL。当在mysql_use_result()之后使用时，当没有更多的行可检索时或如果出现一个错误，mysql_fetch_row()返回NULL。
代码范例：
1 #include <iostream> 2 #include <mysql.h> 3 #include <string> 4 5 #include <assert.h> 6 7 int main() 8 { 9 // 1、初始化MYSQL 实例 10 MYSQL *ms_conn = mysql_init(NULL); 11 if (ms_conn == NULL) 12 { 13 std::cout << "Error: mysql_init failed." << std::endl; 14 return 0; 15 } 16 std::cout << "Info: mysql init successful." << std::endl; 17 18 // 2、连接MYSQL 服务器 19 MYSQL *ms_tmp_res = NULL; 20 ms_tmp_res = mysql_real_connect(ms_conn, "localhost", "root", "123456sx", 21 "suyh", 0, NULL, 0); 22 if (ms_tmp_res == NULL) 23 { 24 std::cout << "Error: connect mysql failed: " << mysql_error(ms_conn) << std::endl; 25 mysql_close(ms_conn), ms_conn = NULL; 26 return 0; 27 } 28 std::cout << "Info: mysql connect successful." << std::endl; 29 30 // 3、执行SQL 语句 31 std::string str_sqls = ""; 32 str_sqls += "SELECT id, account, sex, level, powers FROM player_data WHERE id = 100000 OR id = 100001 OR id = 100002"; 33 34 int res = 0; 35 res = mysql_real_query(ms_conn, str_sqls.c_str(), str_sqls.size()); 36 if (res != 0) 37 { 38 std::cout << "Error: query failed, sql: " << str_sqls.c_str() << std::endl; 39 std::cout << mysql_error(ms_conn) << std::endl; 40 } 41 else 42 { 43 std::cout << "Info: query successful." << std::endl; 44 45 // 取出SQL 语句执行的结果集 46 MYSQL_RES *ms_res = mysql_store_result(ms_conn); 47 if (ms_res != NULL) 48 { 49 // 字段个数 50 unsigned int field_num = mysql_num_fields(ms_res); 51 52 // 每个字段的数据信息 53 MYSQL_FIELD* field_info = mysql_fetch_field(ms_res); 54 assert(field_info != NULL); 55 56 // 每一个字段的值存储在row_data[i] 中，基本都以字符串的形式存储。NULL 的结果 指针也是NULL。 57 // 二进制数据可以通过mysql_fetch_lengths() 函数得到该字段的二进制数据长度，同样以数组形式取出，即：lens[i]; 58 MYSQL_ROW row_data = NULL; // mysql.h --- typedef char **MYSQL_ROW; 59 while (1) 60 { 61 row_data = mysql_fetch_row(ms_res); // 取出下一行结果 62 if (row_data == NULL) 63 break; 64 65 std::cout << "##############################################" << std::endl; 66 for (int i = 0; i < field_num; ++i) 67 { 68 if (row_data[i] == NULL) 69 std::cout << "field name: '" << field_info[i].name << "', values is NULL." << std::endl; 70 else 71 std::cout << "field name: '" << field_info[i].name << "', values is " << row_data[i] << std::endl; 72 } 73 } 74 } 75 76 // 释放结果集 77 mysql_free_result(ms_res), ms_res = NULL; 78 } 79 80 // 使用完释放系统资源 81 mysql_close(ms_conn), ms_conn = NULL; 82 83 return 0; 84 }
