C语言输出sql server数据

要输出 SQL Server 数据，可以使用 ODBC API 和 C 语言编写程序连接到 SQL Server 数据库。以下是一个简单的示例程序，可以用来连接到 SQL Server 数据库，并查询并输出数据。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sql.h>
#include <sqlext.h>

void show_error(unsigned int handletype, const SQLHANDLE& handle, const char* message)
{
    SQLCHAR sqlstate[1024];
    SQLCHAR message[1024];
    if (SQL_SUCCESS == SQLGetDiagRec(handletype, handle, 1, sqlstate, NULL, message, 1024, NULL))
    {
        printf("%s: %s\n", message, sqlstate);
    }
}

int main()
{
    SQLHENV env;
    SQLHDBC dbc;
    SQLHSTMT stmt;
    SQLRETURN ret;
    SQLCHAR outstr[1024];
    SQLSMALLINT outstrlen;

    char* conn_str =
        "Driver={SQL Server};"
        "Server=localhost;"
        "Database=your_database_name;"
        "UID=your_username;"
        "PWD=your_password;";

    // Allocate an environment handle
    SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env);
    SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);
    // Allocate a connection handle
    SQLAllocHandle(SQL_HANDLE_DBC, env, &dbc);
    // Connect to the DSN
    ret = SQLDriverConnect(dbc, NULL, (SQLCHAR*)conn_str, SQL_NTS, outstr, sizeof(outstr), &outstrlen, SQL_DRIVER_NOPROMPT);
    if (SQL_SUCCESS != ret && SQL_SUCCESS_WITH_INFO != ret)
    {
        show_error(SQL_HANDLE_DBC, dbc, "SQLDriverConnect failed");
        return EXIT_FAILURE;
    }
    // Allocate a statement handle
    SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt);
    // Execute the query
    ret = SQLExecDirect(stmt, (SQLCHAR*)"SELECT * FROM your_table_name", SQL_NTS);
    if (SQL_SUCCESS != ret && SQL_SUCCESS_WITH_INFO != ret)
    {
        show_error(SQL_HANDLE_STMT, stmt, "SQLExecDirect failed");
        return EXIT_FAILURE;
    }
    // Fetch and print the results
    SQLCHAR name[1024];
    int age;
    while (SQLFetch(stmt) == SQL_SUCCESS)
    {
        SQLGetData(stmt, 1, SQL_C_CHAR, name, sizeof(name), NULL);
        SQLGetData(stmt, 2, SQL_C_LONG, &age, sizeof(age), NULL);
        printf("%s, %d\n", name, age);
    }
    // Free the statement handle
    SQLFreeHandle(SQL_HANDLE_STMT, stmt);
    // Disconnect
    SQLDisconnect(dbc);
    // Free the connection handle
    SQLFreeHandle(SQL_HANDLE_DBC, dbc);
    // Free the environment handle
    SQLFreeHandle(SQL_HANDLE_ENV, env);

    return EXIT_SUCCESS;
}

在程序中，需要替换 `your_database_name`、`your_username`、`your_password` 和 `your_table_name` 为实际的数据库名称、用户名、密码和表名。然后编译并运行程序即可输出 SQL Server 数据库中的数据。