【SQLite】教程07-C/C++上使用SQLite3

1、配置好C/C++项目环境

2.源码

  1 #include <iostream>
  2 #include <vector>
  3 #include <string>
  4 #include "sqlite3.h"
  5 using namespace std;
  6
  7 //NotUsed：sqlite3_exec()的第4个参数提供的数据
  8 //argc：字段数量
  9 //argv：元素内容的数组
 10 //azColName：字段名称的数组
 11 static int callback(void *NotUsed, int argc, char **argv, char **azColName)
 12 {
 13     for (int i = 0; i < argc; i++)
 14     {
 15         //printf("azColName=%s\n", azColName[i]);
 16         //printf("argv=%s\n", argv[i] ? argv[i] : "NULL");
 17         printf("%s=%s\n", azColName[i], argv[i] ? argv[i] : "NULL");
 18     }
 19     printf("\n");
 20     return 0;
 21 }
 22
 23 int main()
 24 {
 25     //------------------------------------------------------------创建、打开数据库----------------------------------------------------------------
 26     sqlite3 *db = NULL; // 一个打开的数据库实例
 27     const char * path = "..\\Test-SQLite\\Test.db";
 28     int result = sqlite3_open(path, &db);
 29     if (result == SQLITE_OK)
 30     {
 31         std::clog << "打开数据库连接成功!" << endl;
 32     }
 33     else
 34     {
 35         std::clog << "打开数据库连接失败!" << endl;
 36         exit(0);
 37     }
 38     //------------------------------------------------------------创建表----------------------------------------------------------------
 39     char *sql;
 40     char *zErrMsg = 0;
 41     sql = "CREATE TABLE COMPANY("  \
 42         "ID INT PRIMARY KEY     NOT NULL," \
 43         "NAME           TEXT    NOT NULL," \
 44         "AGE            INT     NOT NULL," \
 45         "ADDRESS        CHAR(50)," \
 46         "SALARY         REAL );";
 47
 48     int rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
 49
 50     if (rc != SQLITE_OK)
 51     {
 52         fprintf(stderr, "SQL error: %s\n", zErrMsg);
 53         sqlite3_free(zErrMsg);
 54     }
 55     else
 56     {
 57         fprintf(stdout, "表格创建成功！\n");
 58     }
 59     //--------------------------------------------------------------添加记录--------------------------------------------------------------------
 60     sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "  \
 61         "VALUES (1, 'Paul', 32, 'California', 20000.00 ); " \
 62         "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "  \
 63         "VALUES (2, 'Allen', 25, 'Texas', 15000.00 ); "     \
 64         "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)" \
 65         "VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );" \
 66         "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)" \
 67         "VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 );";
 68     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
 69     if (rc != SQLITE_OK)
 70     {
 71         fprintf(stderr, "SQL error: %s\n", zErrMsg);
 72         sqlite3_free(zErrMsg);
 73     }
 74     else
 75     {
 76         fprintf(stdout, "记录创建成功！\n");
 77     }
 78     //--------------------------------------------------------------查询表--------------------------------------------------------------------
 79     sql = "SELECT * from COMPANY";
 80     //处理每个记录将会用到这个回调callback
 81     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
 82
 83     if (rc != SQLITE_OK)
 84     {
 85         fprintf(stderr, "SQL error: %s\n", zErrMsg);
 86         sqlite3_free(zErrMsg);
 87     }
 88     else
 89     {
 90         fprintf(stdout, "查询操作成功！\n");
 91     }
 92     //--------------------------------------------------------------更新表--------------------------------------------------------------------
 93     sql = "UPDATE COMPANY set SALARY = 88888.00 where ID=1; " \
 94         "SELECT * from COMPANY";
 95     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
 96     if (rc != SQLITE_OK)
 97     {
 98         fprintf(stderr, "SQL error: %s\n", zErrMsg);
 99         sqlite3_free(zErrMsg);
100     }
101     else
102     {
103         fprintf(stdout, "更新表格成功！\n");
104     }
105     //--------------------------------------------------------------查询表 ID=1--------------------------------------------------------------------
106     sql = "SELECT * from COMPANY where ID=1";
107     //处理每个记录将会用到这个回调callback
108     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
109
110     if (rc != SQLITE_OK)
111     {
112         fprintf(stderr, "SQL error: %s\n", zErrMsg);
113         sqlite3_free(zErrMsg);
114     }
115     else
116     {
117         fprintf(stdout, "查询操作成功！\n");
118     }
119     //--------------------------------------------------------------删除记录 ID=2--------------------------------------------------------------------
120     sql = "DELETE from COMPANY where ID=2; " \
121         "SELECT * from COMPANY";
122     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
123     if (rc != SQLITE_OK)
124     {
125         fprintf(stderr, "SQL error: %s\n", zErrMsg);
126         sqlite3_free(zErrMsg);
127     }
128     else {
129         fprintf(stdout, "删除记录成功！\n");
130     }
131     //--------------------------------------------------------------查询表--------------------------------------------------------------------
132     sql = "SELECT * from COMPANY";
133     //处理每个记录将会用到这个回调callback
134     rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
135
136     if (rc != SQLITE_OK)
137     {
138         fprintf(stderr, "SQL error: %s\n", zErrMsg);
139         sqlite3_free(zErrMsg);
140     }
141     else
142     {
143         fprintf(stdout, "查询操作成功！\n");
144     }
145     //--------------------------------------------------------------关闭数据库--------------------------------------------------------------------
146     sqlite3_close(db);
147
148     system("pause");
149     return 0;
150 }

 结果：

4、编码转换

Sqlite的编码默认为UTF-8编码，而vc++工程中所编写的SQL语句,一般是Unciode。由于编码不一致会导致乱码，下面这段程序可以解决：

1).sql语句由GB2312转为UTF-8再用sqlite3_exec()查询

2).查询结果在callback()中由UTF-8转为GB2312再输出

下面是编码转换函数：

//UTF-8到GB2312的转换
char* U2G_(const char* utf8)
{
    int len = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
    wchar_t* wstr = new wchar_t[len + 1];
    memset(wstr, 0, len + 1);
    MultiByteToWideChar(CP_UTF8, 0, utf8, -1, wstr, len);
    len = WideCharToMultiByte(CP_ACP, 0, wstr, -1, NULL, 0, NULL, NULL);
    char* str = new char[len + 1];
    memset(str, 0, len + 1);
    WideCharToMultiByte(CP_ACP, 0, wstr, -1, str, len, NULL, NULL);
    if (wstr) delete[] wstr;
    return str;
}
string U2G(string strutf8)
{
    char cUTF8[500];
    sprintf(cUTF8, "%s", strutf8.c_str());
    string strGB2312;
    strGB2312 = U2G_(cUTF8);
    return strGB2312;
}
int Tools_Use_Record(string strToolName);
//GB2312到UTF-8的转换
char* G2U_(const char* gb2312)
{
    int len = MultiByteToWideChar(CP_ACP, 0, gb2312, -1, NULL, 0);
    wchar_t* wstr = new wchar_t[len + 1];
    memset(wstr, 0, len + 1);
    MultiByteToWideChar(CP_ACP, 0, gb2312, -1, wstr, len);
    len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, NULL, 0, NULL, NULL);
    char* str = new char[len + 1];
    memset(str, 0, len + 1);
    WideCharToMultiByte(CP_UTF8, 0, wstr, -1, str, len, NULL, NULL);
    if (wstr) delete[] wstr;
    return str;
}
string G2U(string strGB2312)
{
    char cGB2312[500];
    sprintf(cGB2312, "%s", strGB2312.c_str());
    string strutf8;
    strutf8 = G2U_(cGB2312);
    return strutf8;
}

5、查询注意

以INTEGER作为条件用=

select * from 表名 where 序号=55

以TEXT作为条件用like

select * from 表名 where 姓名 like '里海'

下面这种写法会出错

select * from 表名 where 姓名='里海'