C++ SQLite轻量化数据库使用总结

官网下载：https://www.sqlite.org/download.html
示例1

cpp 复制代码

#include <iostream>
#include <sqlite3.h>

int main() {
    sqlite3* db;
    char* zErrMsg = 0;
    int rc;

    // 打开数据库连接（如果数据库不存在，则会自动创建）
    rc = sqlite3_open("test.db", &db);
    if (rc) {
        std::cerr << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        return(0);
    } else {
        std::cout << "Opened database successfully" << std::endl;
    }

    // 创建表格
    const char* sqlCreateTable =
        "CREATE TABLE STUDENTS("  \
        "ID INT PRIMARY KEY NOT NULL," \
        "NAME TEXT NOT NULL," \
        "AGE INT NOT NULL);";

    rc = sqlite3_exec(db, sqlCreateTable, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Table created successfully" << std::endl;
    }

    // 插入数据
    const char* sqlInsertData =
        "INSERT INTO STUDENTS (ID, NAME, AGE) " \
        "VALUES (1, 'Alice', 20), " \
        "       (2, 'Bob', 22), " \
        "       (3, 'Charlie', 23);";

    rc = sqlite3_exec(db, sqlInsertData, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Data inserted successfully" << std::endl;
    }

    // 查询数据
    sqlite3_stmt* stmt;
    const char* sqlSelectData = "SELECT * FROM STUDENTS;";
    rc = sqlite3_prepare_v2(db, sqlSelectData, -1, &stmt, 0);
    if (rc != SQLITE_OK) {
        std::cerr << "Failed to select data: " << sqlite3_errmsg(db) << std::endl;
    } else {
        while ((rc = sqlite3_step(stmt)) == SQLITE_ROW) {
            int id = sqlite3_column_int(stmt, 0);
            const unsigned char* name = sqlite3_column_text(stmt, 1);
            int age = sqlite3_column_int(stmt, 2);
            std::cout << "ID: " << id << ", Name: " << name << ", Age: " << age << std::endl;
        }
        sqlite3_finalize(stmt);
    }

    // 更新数据
    const char* sqlUpdateData =
        "UPDATE STUDENTS " \
        "SET AGE = 24 " \
        "WHERE ID = 2;";

    rc = sqlite3_exec(db, sqlUpdateData, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Data updated successfully" << std::endl;
    }

    // 再次查询数据以验证更新结果
    rc = sqlite3_prepare_v2(db, sqlSelectData, -1, &stmt, 0);
    if (rc != SQLITE_OK) {
        std::cerr << "Failed to select data after update: " << sqlite3_errmsg(db) << std::endl;
    } else {
        while ((rc = sqlite3_step(stmt)) == SQLITE_ROW) {
            int id = sqlite3_column_int(stmt, 0);
            const unsigned char* name = sqlite3_column_text(stmt, 1);
            int age = sqlite3_column_int(stmt, 2);
            std::cout << "ID: " << id << ", Name: " << name << ", Age: " << age << std::endl;
        }
        sqlite3_finalize(stmt);
    }

    // 关闭数据库连接
    sqlite3_close(db);
    return 0;
}

关于内容写入及效率优化

文章开始列了一个内容插入与查询的简单例子，下边说一下内容写入提速的几点优化，着重参考https://www.cnblogs.com/rainbowzc/p/6444389.html
- 显示开启事务
- 写同步
- 执行字符串准备
- 高并发模式
下边简单示例

cpp 复制代码

#include <iostream>  
#include <string>  
#include <sstream>  
#include <time.h>  
#include "sqlite3.h"  
  
const int nCount = 500000;  
      
int main (int argc,char** argv)  
{  
    sqlite3* db;  
    sqlite3_open("testdb.db" ,&db);  
    sqlite3_exec(db,"PRAGMA synchronous = OFF; ",0,0,0);  
    sqlite3_exec(db,"drop table if exists t1",0,0,0);  
    sqlite3_exec(db,"create table t1(id integer,x integer,y integer ,weight real)",0,0,0);  
    clock_t t1 = clock();  
      
    sqlite3_exec(db,"begin;",0,0,0);  
    sqlite3_stmt *stmt;  
    const char* sql = "insert into t1 values(?,?,?,?)";  
    sqlite3_prepare_v2(db,sql,strlen(sql),&stmt,0);  
      
    for(int i=0;i<nCount;++i)  
    {  
        // std::stringstream ssm;  
        // ssm<<"insert into t1 values("<<i<<","<<i*2<<","<<i/2<<","<<i*i<<")";  
        // sqlite3_exec(db,ssm.str().c_str(),0,0,0);  
        sqlite3_reset(stmt);  
        sqlite3_bind_int(stmt,1,i);  
        sqlite3_bind_int(stmt,2,i*2);  
        sqlite3_bind_int(stmt,3,i/2);  
        sqlite3_bind_double(stmt,4,i*i);  
        sqlite3_step(stmt);  
    }  
    sqlite3_finalize(stmt);  
    sqlite3_exec(db,"commit;",0,0,0);  
    clock_t t2 = clock();  
      
    sqlite3_close(db);  
      
    std::cout<<"cost tima: "<<(t2-t1)/1000.<<"s"<<std::endl;  
      
    return 0;  
}

使用关键词查询表格

bash 复制代码

- 0.打开数据库连接：使用sqlite3_open打开数据库文件test.db。
- 1.创建表格：使用sqlite3_exec执行SQL语句来创建表格。
- 2.插入数据：使用sqlite3_exec执行SQL语句来插入数据。
- 3.准备和执行查询：
    - 使用sqlite3_prepare_v2准备SQL查询语句。
    - 使用sqlite3_bind_text绑定查询参数（关键词）。
    - 使用sqlite3_step执行查询并迭代结果集。
    - 使用sqlite3_column_int和sqlite3_column_text获取查询结果。
- 4.清理资源：使用sqlite3_finalize释放准备好的语句，使用sqlite3_close关闭数据库连接。

cpp 复制代码

#include <iostream>
#include <sqlite3.h>
#include <string>

void check_error(int rc, sqlite3* db) {
    if (rc) {
        std::cerr << "SQL error: " << sqlite3_errmsg(db) << std::endl;
        sqlite3_close(db);
        exit(rc);
    }
}

int main() {
    sqlite3* db;
    char* zErrMsg = 0;
    int rc;

    // 打开数据库连接
    rc = sqlite3_open("test.db", &db);
    if (rc) {
        std::cerr << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        return rc;
    } else {
        std::cout << "Opened database successfully" << std::endl;
    }

    // 创建表格
    const char* sql_create_table =
        "CREATE TABLE IF NOT EXISTS PERSON("
        "ID INTEGER PRIMARY KEY AUTOINCREMENT,"
        "NAME TEXT NOT NULL,"
        "AGE INTEGER NOT NULL);";

    rc = sqlite3_exec(db, sql_create_table, 0, 0, &zErrMsg);
    check_error(rc, db);

    // 插入数据
    const char* sql_insert_data =
        "INSERT INTO PERSON (NAME, AGE) VALUES ('Alice', 30);"
        "INSERT INTO PERSON (NAME, AGE) VALUES ('Bob', 25);"
        "INSERT INTO PERSON (NAME, AGE) VALUES ('Charlie', 35);";

    rc = sqlite3_exec(db, sql_insert_data, 0, 0, &zErrMsg);
    check_error(rc, db);

    // 查询数据
    std::string keyword = "Alice";
    const char* sql_query = "SELECT * FROM PERSON WHERE NAME LIKE ?;";

    sqlite3_stmt* stmt;
    const char* tail;
    rc = sqlite3_prepare_v2(db, sql_query, -1, &stmt, &tail);
    if (rc != SQLITE_OK) {
        std::cerr << "Failed to prepare statement: " << sqlite3_errmsg(db) << std::endl;
        sqlite3_close(db);
        return rc;
    }

    // 绑定参数
    sqlite3_bind_text(stmt, 1, keyword.c_str(), -1, SQLITE_STATIC);

    // 执行查询
    while ((rc = sqlite3_step(stmt)) == SQLITE_ROW) {
        int id = sqlite3_column_int(stmt, 0);
        const unsigned char* name = sqlite3_column_text(stmt, 1);
        int age = sqlite3_column_int(stmt, 2);
        std::cout << "ID: " << id << ", Name: " << name << ", Age: " << age << std::endl;
    }

    if (rc != SQLITE_DONE) {
        std::cerr << "Execution failed: " << sqlite3_errmsg(db) << std::endl;
    }

    sqlite3_finalize(stmt);
    sqlite3_close(db);

    return 0;
}

创建索引

创建索引会提高查询速度

cpp 复制代码

#include <iostream>
#include <sqlite3.h>

int main() {
    sqlite3 *db;
    char *zErrMsg = 0;
    int rc;

    // 打开数据库连接
    rc = sqlite3_open("test.db", &db);
    if (rc) {
        std::cerr << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        return(0);
    } else {
        std::cout << "Opened database successfully" << std::endl;
    }

    // 创建表
    const char *sqlCreateTable = 
        "CREATE TABLE COMPANY("  \
        "ID INT PRIMARY KEY     NOT NULL," \
        "NAME           TEXT    NOT NULL," \
        "AGE            INT     NOT NULL," \
        "ADDRESS        CHAR(50)," \
        "SALARY         REAL );";

    rc = sqlite3_exec(db, sqlCreateTable, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Table created successfully" << std::endl;
    }

    // 创建索引
    const char *sqlCreateIndex = 
        "CREATE INDEX idx_name ON COMPANY(NAME);";

    rc = sqlite3_exec(db, sqlCreateIndex, 0, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        std::cerr << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    } else {
        std::cout << "Index created successfully" << std::endl;
    }

    // 关闭数据库连接
    sqlite3_close(db);
    return 0;
}

参考：

1.https://blog.csdn.net/zearot/article/details/51039593