My C++ Wrapper for FreeTDS

最新推荐文章于 2023-03-12 23:34:30 发布

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本文介绍了一个用于FreeTDS MSSql Server接口的C++封装类，该类简化了数据库连接、断开及执行SQL命令的过程。支持基本的CRUD操作，并提供错误处理功能。

This artical introduce you my C++ wrapper for FreeTDS MSSqlServer interface.

With this wrapper you can easily connect/disconnect sqlserver database, and execute insert/delete/update/select/create table commands.

This wrapper is not thread-safe and not fully tested. Leave me your better suggestions will be a good help.

You are free to use it in any way, but the author name should always be there.

//FreeTDSHelper.h //author: huanghaifeng #ifndef FREETDSHELPER_H #define FREETDSHELPER_H #include <stdio.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include </user/local/freetds/include/sybfront.h> #include </user/local/freetds/include/sybdb.h> #define MAX_ROWS 1024 #define ERR_MSG_LEN 1024 struct FIELD { char* data; int bufSize; FIELD(int size):data(NULL),bufSize(size) { data = new char[size]; } ~FIELD() { if(data!=NULL)delete[] data; data=NULL; } }; struct ROW { int colcount; int* fieldLens; FIELD** fields; ROW(int* fLens, int columncount):fields(NULL),colcount(columncount),fieldLens(fLens) { fields = new FIELD*[columncount]; for(int i=0;i<columncount;++i) { fields[i] = new FIELD(fieldLens[i]); } } ~ROW() { if(fields!=NULL) { for(int i=0;i<colcount;++i) { delete fields[i]; fields[i]=NULL; } delete[] fields; fields=NULL; } } char* getField(int fieldNum) { return fields[fieldNum]->data; } }; //sqlserver wrapper, not thread-safe class FreeTDSHelper { public: FreeTDSHelper(); ~FreeTDSHelper(); /********************************************** *功能: 打开指定数据库 *入参: 1,server为数据库主机,如192.168.90.5:1433 * 2,user为数据库帐号 * 3,password为数据库密码 * 4,dbname为数据库名 * 5,charset为字符集,默认为gbk **********************************************/ bool openDB(char* server, char* user, char* password, char* dbname, char* charset=NULL); /********************************************** *功能: 关闭当前数据库 **********************************************/ bool closeDB(); /********************************************** *功能: 增加, 删除, 修改, 建表 **********************************************/ bool execute(char* sql); /********************************************** *功能: 查询 *入参: 1,sql是查询语句 * 2,maxRowCount表示需要缓存的最大行数 *返回: >=0代表结果集的行数, <0代表失败 **********************************************/ int query(char* sql, int maxRowCount=MAX_ROWS); /********************************************** *功能: 取第rownum行 **********************************************/ ROW* getRow(int rownum); /********************************************** *功能: 每次用完query必须调用此函数清理结果集 **********************************************/ bool releaseResultSet(); /********************************************** *功能: 返回当前结果集的行数 **********************************************/ int getRowCount() const; /********************************************** *功能: 返回当前结果集的列数 **********************************************/ int getColumnCount() const; /********************************************** *功能: 返回上一个操作的错误信息 **********************************************/ char* getErrorMessage(); private: FreeTDSHelper(const FreeTDSHelper&); FreeTDSHelper& operator=(const FreeTDSHelper&); LOGINREC* loginrec; DBPROCESS* dbprocess; int rowCount; int colCount; int* pBufSize; ROW* currentRow; bool prepareRowBuffer(); bool destroyRowBuffer(); char errMsg[ERR_MSG_LEN]; }; #endif //FREETDSHELPER_H

//FreeTDSHelper.cpp //author: huanghaifeng #include "FreeTDSHelper.h" FreeTDSHelper::FreeTDSHelper() :loginrec(NULL),dbprocess(NULL),currentRow(NULL),rowCount(0),colCount(0),pBufSize(NULL) { memset(errMsg,0,ERR_MSG_LEN); dbinit(); } FreeTDSHelper::~FreeTDSHelper() { closeDB(); } bool FreeTDSHelper::openDB(char* server, char* user, char* password, char* dbname, char* charset) { if(server==NULL || dbname==NULL) { sprintf(errMsg,"Server-address or db-name you supplied is null, that is not allowed."); return false; } closeDB(); loginrec = dblogin(); DBSETLUSER(loginrec, user); DBSETLPWD(loginrec, password); DBSETLCHARSET(loginrec,charset==NULL?"GBK":charset); dbprocess = dbopen(loginrec, server); if(dbprocess == FAIL) { sprintf(errMsg,"dbopen error, can not connect to db-server."); dbloginfree(loginrec); loginrec=NULL; return false; } //选定数据库 if(dbuse(dbprocess, dbname) == FAIL) { sprintf(errMsg,"dbuse error, can not use your chosen db."); dbclose(dbprocess); dbprocess=NULL; dbloginfree(loginrec); loginrec=NULL; return false; } return true; } bool FreeTDSHelper::closeDB() { if((dbprocess!=FAIL) || (dbprocess!=NULL)) { if(currentRow != NULL) { releaseResultSet(); } dbclose(dbprocess); dbprocess=NULL; } if(loginrec != NULL) { dbloginfree(loginrec); loginrec=NULL; } } bool FreeTDSHelper::execute(char* sql) { //发送增删改命令 dbcmd(dbprocess, sql); if(dbsqlexec(dbprocess) == FAIL) { snprintf(errMsg,ERR_MSG_LEN-1,"dbsqlexec error(%s)",sql); return false; } return true; } int FreeTDSHelper::query(char * sql, int maxRowCount) { if(sql==NULL) { sprintf(errMsg,"Your sql string is null."); return -1; } //设置缓存, 最多缓存行数为MAX_ROWS char bufLen[16]={0}; sprintf(bufLen,"%d",maxRowCount); if(dbsetopt(dbprocess,DBBUFFER,bufLen,sizeof(bufLen)) == FAIL) { sprintf(errMsg,"dbsetopt error, can not set buffer."); return -1; } releaseResultSet(); //发送查询命令 dbcmd(dbprocess, sql); if(dbsqlexec(dbprocess) == FAIL) { snprintf(errMsg,ERR_MSG_LEN-1,"dbsqlexec error(%s)",sql); return -1; } //获取结果集并计算行数 DBINT result_code; while ((result_code = dbresults(dbprocess)) != NO_MORE_RESULTS) { if (result_code == SUCCEED) { while (dbnextrow(dbprocess) != NO_MORE_ROWS) { ++rowCount; if(rowCount>MAX_ROWS) { sprintf(errMsg,"Not enough buffer to hold all rows."); return -1; } } } } //准备一行数据所需的内存 prepareRowBuffer(); //绑定一行数据每列的内存 for(int i=0;i<colCount;++i) { if(dbbind(dbprocess, i+1, CHARBIND, (DBCHAR)0, (BYTE*)(currentRow->getField(i))) == FAIL) { sprintf(errMsg, "dbbind error, the column number given isn't valid, or / the vartype isn't compatible with the sqlserver data type being returned, or varaddr is null."); return -1; } } return rowCount; } ROW* FreeTDSHelper::getRow(int rownum) { for(int i=0;i<colCount;++i) { memset(currentRow->getField(i), 0, pBufSize[i]); } //每调用一次dbgetrow, 被绑定的内存就会更新一次 dbgetrow(dbprocess,rownum+1); return currentRow; } bool FreeTDSHelper::releaseResultSet() { dbfreebuf(dbprocess); rowCount=0; colCount=0; destroyRowBuffer(); return true; } bool FreeTDSHelper::prepareRowBuffer() { //求列数 colCount = dbnumcols(dbprocess); //分配空间存放各列的长度 pBufSize = new int[colCount]; //求各列的数据长度 for(int i=1;i<=colCount;i++) { pBufSize[i-1] = dbcollen(dbprocess, i); } //分配一行空间 currentRow = new ROW(pBufSize, colCount); return true; } bool FreeTDSHelper::destroyRowBuffer() { if(currentRow!=NULL) { delete currentRow; currentRow=NULL; } if(pBufSize!=NULL) { delete[] pBufSize; pBufSize=NULL; } return true; } int FreeTDSHelper::getRowCount() const { return rowCount; } int FreeTDSHelper::getColumnCount() const { return colCount; } char* FreeTDSHelper::getErrorMessage() { return errMsg; }

//main.cpp //author: huanghaifeng #include "FreeTDSHelper.h" #include <iostream> using std::cin; int selectAndPrintTable(FreeTDSHelper& helper, char* sql) { //查询 if(helper.query(sql) == -1) { printf("%s/n", helper.getErrorMessage()); return -1; } printf("there are %d rows, %d columns/n", helper.getRowCount(), helper.getColumnCount()); for(int i=0; i<helper.getRowCount(); ++i) { ROW* r = helper.getRow(i); for(int j=0; j<helper.getColumnCount(); ++j) { printf("%s/t", r->getField(j)); } printf("/n"); } helper.releaseResultSet();//查询后必须调用释放空间 return 0; } int main() { printf("----------------------------------------/n"); FreeTDSHelper helper; #if 1 if(helper.openDB("192.168.90.5:1433","sa","123456","test") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } //查询 if(selectAndPrintTable(helper, "select * from table1") == -1) return -1; printf("----------------------------------------/n"); printf("press enter to update table/n"); cin.get(); //修改 if(helper.execute("update table1 set name='Anthony' where id = 1") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } //查询 if(selectAndPrintTable(helper, "select * from table1") == -1) return -1; printf("----------------------------------------/n"); printf("press enter to insert one row to table/n"); cin.get(); //插入 if(helper.execute("insert into table1 values(7,'Rock')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } //查询 if(selectAndPrintTable(helper, "select * from table1") == -1) return -1; printf("----------------------------------------/n"); printf("press enter to delete one row from table/n"); cin.get(); //删除 if(helper.execute("delete from table1 where id = 7") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } //查询 if(selectAndPrintTable(helper, "select * from table1") == -1) return -1; printf("----------------------------------------/n"); #endif #if 1 printf("press enter to create table2 and insert rows into it/n"); cin.get(); //建表后插入 if(helper.execute("create table table2(id int, name varchar(32), addr varchar(512))") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } if(helper.execute("insert into table2 values(1,'Rock1','belibala~~~~~belibala')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } if(helper.execute("insert into table2 values(2,'Rock2','belibala~~~~~belibala~~~~~belibala')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } if(helper.execute("insert into table2 values(3,'Rock3','belibala~~~~~belibala~~~~~belibala~~~~~belibala')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } if(helper.execute("insert into table2 values(4,'Rock4','belibala~~~~~belibala~~~~~belibala~~~~~belibala~~~~~belibala')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } if(helper.execute("insert into table2 values(5,'Rock5','belibala~~~~~belibala~~~~~belibala~~~~~belibala~~~~~belibala~~~~~belibala')") == false) { printf("%s/n",helper.getErrorMessage()); return -1; } //查询 if(selectAndPrintTable(helper, "select * from table2") == -1) return -1; printf("----------------------------------------/n"); #endif return 0; }