c语⾔数据库查询系统,C语⾔实现sqlite3数据库查询的基本⽅ 法 sqlite回传函数相关 说了3种基本⽅法：callback，gettable和预处理stmt⽅法 下⾯给出测试代码和测试⽤数据库，代码如下 #include #include #include #include "sqlite3.h" // //typedef int (*sqlite3_callback)( // void* data, /* Data provided in the 4th argument of sqlite3_exec() */ // int ncols, /* The number of columns in row */ // char** values, /* An array of strings representing fields in the row */ // char** headers /* An array of strings representing column names */ //); int callback(void* data, int ncols, char** values, char** headers) { int i; int len =0; int ll=0; for(i=0; i < ncols; i++) { if(strlen(headers[i])>len) len = strlen(headers[i]); } for(i=0; i < ncols; i++) { ll = len-strlen(headers[i]); while(ll) { fprintf(stdout," "); --ll; } fprintf(stdout, "%s: %sn", headers[i], values[i]); } fprintf(stdout, "n"); return 0; } int search_by_callback(const char* db_name, const char* sql_cmd) { int i = 0 ; int j = 0 ; int nrow = 0, ncolumn = 0; char **azResult; //⼆维数组存放结果 sqlite3 *db=NULL; char *zErrMsg = 0; int rc; int len=0; if(access(db_name, 0) == -1) { fprintf(stderr, "%s not foundn", db_name); return -1; } rc = sqlite3_open(db_name, &db); if( rc != SQLITE_OK) { fprintf(stderr, "%s open failed: %sn", db_name,sqlite3_errmsg(db)); sqlite3_close(db); return -1; } //查询数据 rc = sqlite3_exec( db,sql_cmd, callback, NULL, &zErrMsg ); if( rc != SQLITE_OK) { fprintf(stderr, "%s %s: %sn", db_name,sql_cmd, sqlite3_errmsg(db)); if(zErrMsg) { fprintf(stderr,"ErrMsg = %s n", zErrMsg); sqlite3_free(zErrMsg); } sqlite3_close(db); return -1; } if(zErrMsg) { sqlite3_free(zErrMsg); } //关闭数据库 sqlite3_close(db); return 0; } int search_by_table(const char* db_name, const char* sql_cmd) { int i = 0 ; int j = 0 ; int nrow = 0, ncolumn = 0; char **azResult; //⼆维数组存放结果 sqlite3 *db=NULL; char *zErrMsg = 0; int rc; int len=0; if(access(db_name, 0) == -1) { fprintf(stderr, "%s not foundn", db_name); return -1; } rc = sqlite3_open(db_name, &db); if( rc != SQLITE_OK) { fprintf(stderr, "%s open failed: %sn"
