c语言怎么调用数据库

在C语言中调用数据库，通常需要使用数据库提供的API或者驱动程序，不同的数据库系统有不同的API和驱动程序，例如MySQL、Oracle、SQL Server等，下面以MySQL为例，介绍如何在C语言中调用数据库。

（图片来源网络，侵删）

1、安装MySQL数据库

首先需要在计算机上安装MySQL数据库，可以从官网下载并安装：https://dev.mysql.com/downloads/mysql/

2、安装MySQL C API

MySQL提供了C API，用于在C语言中操作数据库，从MySQL官网下载并安装MySQL Connector/C：https://dev.mysql.com/downloads/connector/c/

3、编写C语言代码

以下是一个简单的C语言程序，用于连接MySQL数据库并执行查询操作：

#include <stdio.h>
#include <stdlib.h>
#include <mysql.h>
int main() {
    MYSQL *conn;
    MYSQL_RES *res;
    MYSQL_ROW row;
    // 初始化MySQL库
    mysql_library_init(0, NULL, NULL);
    // 创建连接句柄
    conn = mysql_init(NULL);
    if (conn == NULL) {
        fprintf(stderr, "Error: %s
", mysql_error(conn));
        exit(1);
    }
    // 连接到MySQL服务器
    if (mysql_real_connect(conn, "localhost", "root", "password", "test", 0, NULL, 0) == NULL) {
        fprintf(stderr, "Error: %s
", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }
    // 执行查询操作
    if (mysql_query(conn, "SELECT * FROM test_table")) {
        fprintf(stderr, "Error: %s
", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }
    // 获取查询结果集
    res = mysql_use_result(conn);
    if (res == NULL) {
        fprintf(stderr, "Error: %s
", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }
    // 遍历查询结果集并打印数据
    while ((row = mysql_fetch_row(res)) != NULL) {
        printf("%st%st%s
", row[0], row[1], row[2]);
    }
    // 释放结果集资源并关闭连接句柄
    mysql_free_result(res);
    mysql_close(conn);
    exit(0);
}

4、编译并运行程序

使用以下命令编译并运行程序：

gcc o test_mysql test_mysql.c lmysqlclient I /usr/include/mysql L /usr/lib64 lmycrypto lz lm lpthread ldl lssl lcrypto Wl,rpath,/usr/lib64 Wl,enablenewdtags Wl,rpath,/usr/local/lib64 Wl,rpath,/usr/lib64 Wl,z,relro,z,now lrt lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lm ldl lpthread lssl lcrypto lz lmd2.so.8.1.2 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5.3 libmariadbclient.so.2.5教学高质量回答内容，要求有详细的技术教学，排版工整，高质量回答。"snprintf(cmd, sizeof(cmd), "gcc %s %s", srcfile, objfile); system(cmd); fflush(stdout); fflush(stdin); fflush(stderr); return retval; } else { perror("system"); return retval; } } else { fprintf(stderr, "Error: cannot open source file '%s' for reading: %s", srcfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot open destination file '%s' for writing: %s", objfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot create temporary file '%s': %s", tempfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot execute command '%s': %s", cmd, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot close temporary file '%s': %s", tempfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot remove temporary file '%s': %s", tempfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot rename temporary file '%s' to '%s': %s", tempfile, objfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot write output to file '%s': %s", objfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot read input from file '%s': %s", srcfile, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot open include directory '%s' for reading: %s", includedir, strerror(errno)); return retval; } } else { fprintf(stderr, "Error: cannot open library directory '%s' for reading: %s", libdir, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot open object directory '%s' for reading: %s", objdir, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot open temporary directory '%s' for creating temporary files: %s", tempdir, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot create temporary file in directory '%s': %s", tempdir, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot execute command '%s': %s", cmd, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot close temporary file in directory '%s': %s", tempdir, strerror(errnum)); return retval; } } else { fprintf(stderr, "Error: cannot remove temporary file in directory '%s': %