调用API对Mysql数据库实现增删改查以及事务实现

Posted 2020-10-14 *平凡*随风舞

使用API实现增删改查客户端代码:

#include <stdio.h>
#include <mysql.h>
#include <string.h>
#include <unistd.h>

#define _HOST_NAME_ "127.0.0.1"
#define _ACT_NAME_	"root"
#define _ACT_PWD_	"123"
#define _DB_NAME_	"scott"

void showResult(MYSQL_RES * result)
{
	 MYSQL_FIELD *field;
	 int numfield = mysql_num_fields(result);
	 while(field = mysql_fetch_field(result))
	 {
	 		printf("%-7s\t",field->name);
	 }
	 printf("\n--------------------------------------------------------------\n");
	 
	 MYSQL_ROW row;
	 while (row = mysql_fetch_row(result)) {
		 	int i;
		 	for(i = 0;i < numfield;i++){
		 		printf("%-7s\t",row[i]);
		 	}	 
		 	printf("\n");
	 }
	 printf("--------------------------------------------------------------\n");
}

int main()
{
	//初始化MYSQL
	MYSQL *mysql = mysql_init(NULL);
	if(mysql == NULL){
		printf("init err\n");
		return -1;
	}
	//建立连接
	mysql = mysql_real_connect(mysql,_HOST_NAME_,_ACT_NAME_,
		_ACT_PWD_,_DB_NAME_,0,NULL,0);
	if(mysql == NULL){
		fprintf(stderr, "Failed to connect to database: Error: %s\n",
          mysql_error(mysql));
		return -2;
	}
	//设置字符集
	mysql_set_character_set(mysql, "utf8");
	printf("connected ok!\n");
	
	char rsql[512] ={0};
	while(1){
			write(STDOUT_FILENO,"sql>",4);
			memset(rsql,0,sizeof(rsql));
			read(STDIN_FILENO,rsql,sizeof(rsql));
			//判断是quit则退出
			if(strncasecmp(rsql,"quit",4) == 0){
					printf("bye!\n");
					break;
			}
			else if( mysql_query(mysql,rsql) ){
				fprintf(stderr, "Failed to query to database: Error: %s\n",
          mysql_error(mysql));
				continue;
			}
			//获取记录集
			MYSQL_RES *result = mysql_store_result(mysql);
			if(result != NULL){
				showResult(result);
				//释放记录集
				mysql_free_result(result);
			}
			else{
				printf("Query OK, %ld row affected \n",(long) mysql_affected_rows(mysql));
			}
	}
	mysql_close(mysql);
	return 0;
}

　

 

使用API操作事务:

//mysql中的事务
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mysql.h"

#define SET_TRAN	"SET AUTOCOMMIT=0"  		//手动commit	————手动commit
#define UNSET_TRAN	"SET AUTOCOMMIT=1"			//自动commit

#define _HOST_ "127.0.0.1"
#define _USER_ "root"
#define _PASSWD_ "123"
#define _DBNAME_ "scott"

//设置事务为手动提交
int mysql_OperationTran(MYSQL *mysql)  			
{
	//--开启事务
	int ret = mysql_query(mysql, "start transaction");  //开启一次事务 start transaction
	if (ret != 0) {
		printf("mysql_OperationTran query start err: %s\n", mysql_error(mysql));
		return ret;
	}

	//--设置事务为手动提交
	ret = mysql_query(mysql, SET_TRAN);			//set　autocommmit = 0
	if (ret != 0) {
		printf("mysql_OperationTran query set err: %s\n", mysql_error(mysql));
		return ret;
	}

	return ret;
}

//设置事务为自动提交
int mysql_AutoTran(MYSQL *mysql)
{
	//--开启事务
	int ret = mysql_query(mysql, "start transaction");  
	if (ret != 0) {
		printf("mysql_AutoTran query start err: %s\n", mysql_error(mysql));
		return ret;
	}

	//--设置事务为自动提交
	ret = mysql_query(mysql, UNSET_TRAN);  //"set autocommit = 1"
	if (ret != 0) {
		printf("mysql_AutoTran query set err: %s\n", mysql_error(mysql));
		return ret;
	}

	return ret;		
}

//执行commit，手动提交事务
int mysql_Commit(MYSQL *mysql)
{
	int ret = mysql_query(mysql, "COMMIT"); //提交
	if (ret != 0) {
		printf("commit err: %s\n", mysql_error(mysql));
		return ret;
	}
	return ret;
}

//执行rollback，回滚事务		
int mysql_Rollback(MYSQL *mysql)
{
	int ret = mysql_query(mysql, "ROLLBACK");
	if (ret != 0) {
		printf("rollback err: %s\n", mysql_error(mysql));
		return ret;
	}
	return ret;
	
}

#define DROP_SAMPLE_TABLE "DROP TABLE IF EXISTS test_table"
#define CREATE_SAMPLE_TABLE "CREATE TABLE test_table(col1 INT,                                                 col2 VARCHAR(10),                                                 col3 VARCHAR(10))"
                                                                                       
#define sql01 "INSERT INTO test_table(col1,col2,col3) VALUES(10, ‘AAA‘, ‘A1‘)"
#define sql02 "INSERT INTO test_table(col1,col2,col3) VALUES(20, ‘BBB‘, ‘B2‘)"
#define sql03 "INSERT INTO test_table(col1,col2,col3) VALUES(30, ‘CCC‘, ‘C3‘)"
#define sql04 "INSERT INTO test_table(col1,col2,col3) VALUES(40, ‘DDD‘, ‘D4‘)"

int main(void)
{
	int ret = 0;

	MYSQL *mysql = mysql_init(NULL);
	
	mysql = mysql_real_connect(mysql, _HOST_, _USER_, _PASSWD_, _DBNAME_, 0, NULL, 0);
	if (mysql == NULL) {
		ret = mysql_errno(mysql);
		printf("func mysql_real_connect() err：%d\n", ret);
		return ret;
	} 	
	printf(" --- connect ok......\n");	
	//执行删除表
	if (mysql_query(mysql, DROP_SAMPLE_TABLE)) {
	  fprintf(stderr, " DROP TABLE failed\n");
	  fprintf(stderr, " %s\n", mysql_error(mysql));
	  exit(0);
	}
	//执行创建表
	if (mysql_query(mysql, CREATE_SAMPLE_TABLE)) {
	  fprintf(stderr, " CREATE TABLE failed\n");
	  fprintf(stderr, " %s\n", mysql_error(mysql));
	  exit(0);
	}	
	
	ret = mysql_OperationTran(mysql); 	//开启事务，并修改事务属性为手动commit 
	if (ret != 0) {
		printf("mysql_OperationTran() err:%d\n", ret);
		return ret;
	}
	
	ret = mysql_query(mysql, sql01);	//向表中插入第一行数据 ‘AAA’
	if (ret != 0) {
		printf("mysql_query() err:%d\n", ret);
		return ret;
	}
	
	ret = mysql_query(mysql, sql02);	//向表中插入第二行数据 ‘BBB’
	if (ret != 0) {
		printf("mysql_query() err:%d\n", ret);
		return ret;
	}
	
	ret = mysql_Commit(mysql); 			//手动提交事务
	if (ret != 0) {
		printf("mysql_Commit() err:%d\n", ret);
		return ret;
	}
	//////////AAA BBB  进去了。
	
#if 1
	ret = mysql_AutoTran(mysql); 		// =再次= 修改事务属性为【自动】commit
	if (ret != 0) {
		printf("mysql_OperationTran() err:%d\n", ret);
		return ret;
	}
#else 
	ret = mysql_OperationTran(mysql); 	// =再次= 修改事务属性为【手动】commit
	if (ret != 0) {
		printf("mysql_OperationTran() err:%d\n", ret);
		return ret;
	}
#endif

	ret = mysql_query(mysql, sql03);	//向表中插入第三行数据 ‘CCC’
	if (ret != 0) {
		printf("mysql_query() err:%d\n", ret);
		return ret;
	}
	
	ret = mysql_query(mysql, sql04);	//向表中插入第四行数据 ‘DDD’
	if (ret != 0) {
		printf("mysql_query() err:%d\n", ret);
		return ret;
	}
	
	ret = mysql_Rollback(mysql);		//直接rollback操作
	if (ret != 0) {
		printf("mysql_Rollback() err:%d\n", ret);
		return ret;
	}
	
	//rollback操作是否能回退掉CCC、DDD的值，取决于事务属性。
	
	mysql_close(mysql);
	
	return 0;	
}