cmd.SetCommandText(sql)什么意思
时间: 2024-04-18 14:30:40 浏览: 13
`cmd.SetCommandText(sql)` 是一个假设的方法调用示例。该方法用于设置命令对象(`cmd`)的文本属性,以便执行指定的 SQL 查询或命令。
在这个例子中,`cmd` 可能是一个表示数据库连接的对象,而 `sql` 则是一个包含要执行的 SQL 查询或命令的字符串。
通过调用 `SetCommandText(sql)` 方法,可以将要执行的 SQL 查询或命令指定为 `sql` 字符串的内容。这样,当执行该命令时,数据库将根据指定的文本执行相应的操作。
请注意,这只是一个假设的示例,具体实现可能因编程语言、数据库访问库或框架而有所不同。实际情况下,请参考相应的文档和代码库来了解正确的用法和语法。
相关问题
CADOConn conn; std::wstring strConn = L"Provider=SQLOLEDB;Data Source=127.0.0.1;Initial Catalog=SQL_PLC;User Id=sa;Password=bme12345;"; std::wstring strSQL; if (!conn.Open(strConn)) { std::cerr << "Failed to connect to database!" << std::endl; return -1; } // 插入数据 strSQL = L"INSERT INTO plcdata (出水压力,瞬时流量,总流量,当日运行次数,运行总次数) VALUES (2,2,5,2,0)"; if (!conn.Add(strSQL)) { std::cerr << "Failed to insert data!" << std::endl; } 参数化查询
参数化查询可以有效避免SQL注入攻击,同时也能提高查询效率和安全性。修改上述代码以使用参数化查询,可以参考以下示例:
```
CADOConn conn;
std::wstring strConn = L"Provider=SQLOLEDB;Data Source=127.0.0.1;Initial Catalog=SQL_PLC;User Id=sa;Password=bme12345;";
std::wstring strSQL;
if (!conn.Open(strConn))
{
std::cerr << "Failed to connect to database!" << std::endl;
return -1;
}
// 插入数据
strSQL = L"INSERT INTO plcdata (出水压力,瞬时流量,总流量,当日运行次数,运行总次数) VALUES (?, ?, ?, ?, ?)";
CADOCommand cmd(&conn);
cmd.SetCommandText(strSQL.c_str());
cmd.AddParameter(L"出水压力", adInteger, adParamInput, 0, 2);
cmd.AddParameter(L"瞬时流量", adInteger, adParamInput, 0, 2);
cmd.AddParameter(L"总流量", adInteger, adParamInput, 0, 5);
cmd.AddParameter(L"当日运行次数", adInteger, adParamInput, 0, 2);
cmd.AddParameter(L"运行总次数", adInteger, adParamInput, 0, 0);
if (!cmd.Execute())
{
std::cerr << "Failed to insert data!" << std::endl;
}
```
以上代码中,使用参数占位符 "?" 替换了具体数值,同时在 CADOCommand 对象中添加了对应的参数,类型为 adInteger,表示整型参数。在执行 cmd.Execute() 时,会自动将参数值填充到 SQL 语句中,然后执行插入操作。
C语言用ADO插入sqlserver数据库
要在C语言中使用ADO插入SQL Server数据库,你需要使用OLE DB API。以下是一个简单的示例代码,可以将数据插入到数据库中:
```c
#include <stdio.h>
#include <windows.h>
#include <oledb.h>
int main() {
// 定义变量
HRESULT hr;
IDBInitialize *pInitialize = NULL;
IDBCreateSession *pCreateSession = NULL;
IDBCreateCommand *pCreateCommand = NULL;
ICommandText *pCommandText = NULL;
IAccessor *pAccessor = NULL;
IRowset *pRowset = NULL;
HACCESSOR hAccessor = NULL;
DBBINDING dbBinding[3];
BYTE pData[3][50] = { "val1", "val2", "val3" };
// 初始化COM组件
CoInitialize(NULL);
// 创建数据库连接
hr = CoCreateInstance(CLSID_SQLSERVER, NULL, CLSCTX_ALL, IID_IDBInitialize, (void**)&pInitialize);
hr = pInitialize->Initialize();
hr = pInitialize->QueryInterface(IID_IDBCreateSession, (void**)&pCreateSession);
// 创建数据库会话
hr = pCreateSession->CreateSession(NULL, IID_IDBCreateCommand, (IUnknown**)&pCreateCommand);
hr = pCreateCommand->CreateCommand(NULL, IID_ICommandText, (IUnknown**)&pCommandText);
// 设置SQL语句
hr = pCommandText->SetCommandText(DBGUID_DBSQL, "INSERT INTO myTable (col1, col2, col3) VALUES (?, ?, ?)");
// 绑定参数
dbBinding[0].iOrdinal = 1;
dbBinding[0].dwPart = DBPART_VALUE;
dbBinding[0].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
dbBinding[0].eParamIO = DBPARAMIO_INPUT;
dbBinding[0].cbMaxLen = 50;
dbBinding[0].pTypeInfo = NULL;
dbBinding[0].pObject = NULL;
dbBinding[0].pBindExt = NULL;
dbBinding[0].wType = DBTYPE_STR;
dbBinding[0].bPrecision = 0;
dbBinding[0].bScale = 0;
dbBinding[0].obValue = 0;
dbBinding[0].obLength = 0;
dbBinding[0].obStatus = 0;
dbBinding[1].iOrdinal = 2;
dbBinding[1].dwPart = DBPART_VALUE;
dbBinding[1].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
dbBinding[1].eParamIO = DBPARAMIO_INPUT;
dbBinding[1].cbMaxLen = 50;
dbBinding[1].pTypeInfo = NULL;
dbBinding[1].pObject = NULL;
dbBinding[1].pBindExt = NULL;
dbBinding[1].wType = DBTYPE_STR;
dbBinding[1].bPrecision = 0;
dbBinding[1].bScale = 0;
dbBinding[1].obValue = 50;
dbBinding[1].obLength = 0;
dbBinding[1].obStatus = 0;
dbBinding[2].iOrdinal = 3;
dbBinding[2].dwPart = DBPART_VALUE;
dbBinding[2].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
dbBinding[2].eParamIO = DBPARAMIO_INPUT;
dbBinding[2].cbMaxLen = 50;
dbBinding[2].pTypeInfo = NULL;
dbBinding[2].pObject = NULL;
dbBinding[2].pBindExt = NULL;
dbBinding[2].wType = DBTYPE_STR;
dbBinding[2].bPrecision = 0;
dbBinding[2].bScale = 0;
dbBinding[2].obValue = 100;
dbBinding[2].obLength = 0;
dbBinding[2].obStatus = 0;
hr = pCommandText->QueryInterface(IID_IAccessor, (void**)&pAccessor);
hr = pAccessor->CreateAccessor(DBACCESSOR_PARAMETERDATA, 3, dbBinding, 0, &hAccessor, NULL);
// 执行SQL语句
hr = pCommandText->Execute(NULL, IID_IRowset, NULL, NULL, (IUnknown**)&pRowset);
hr = pAccessor->ReleaseAccessor(hAccessor, NULL);
hr = pRowset->Release();
hr = pAccessor->Release();
hr = pCommandText->Release();
hr = pCreateCommand->Release();
hr = pCreateSession->Release();
hr = pInitialize->Release();
// 释放COM组件
CoUninitialize();
return 0;
}
```
这个代码中,`myTable` 是你要插入数据的表名,`col1`、`col2`、`col3` 分别是表中的列名。你需要将这些信息替换为你自己的信息。最后,通过执行 `pCommandText->Execute` 函数来执行插入操作。