How does the C++ function library perform database management?-C++-php.cn

How does the C++ function library perform database management?

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Release： 2024-04-18 14:15:02

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C function library can be used for database management. It provides a series of functions through the <sqlite3.h> header file to support operations such as connection, table creation, data insertion, query, and transaction processing. The library is suitable for management and database interaction. common tasks.

C++ 函数库如何进行数据库管理？

C function library for database management

C The standard library provides a wide range of functions to handle common functions related to database interaction. Task. These function libraries mainly come from the <sqlite3.h> header file.

Connect to the database

sqlite3 *db;
int rc = sqlite3_open("database.db", &db);

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Create table

char *zErrMsg = 0;
int rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS mytable (id INTEGER PRIMARY KEY, name TEXT)", NULL, 0, &zErrMsg);

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Insert data

sqlite3_stmt *stmt;
sqlite3_prepare_v2(db, "INSERT INTO mytable (name) VALUES (?)", -1, &stmt, NULL);
sqlite3_bind_text(stmt, 1, "John Doe", -1, SQLITE_STATIC);
sqlite3_step(stmt);
sqlite3_finalize(stmt);

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Query data

sqlite3_stmt *stmt;
sqlite3_prepare_v2(db, "SELECT name FROM mytable WHERE id=?", -1, &stmt, NULL);
sqlite3_bind_int(stmt, 1, 1);
while (sqlite3_step(stmt) == SQLITE_ROW) {
    printf("%s\n", sqlite3_column_text(stmt, 0));
}
sqlite3_finalize(stmt);

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Transaction processing

sqlite3_exec(db, "BEGIN TRANSACTION");
// 执行多条查询
sqlite3_exec(db, "COMMIT");

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Practical case: managing student information database

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

using namespace std;

int main() {
    sqlite3 *db;
    int rc = sqlite3_open("students.db", &db);
    if (rc) {
        cerr << "Error opening database: " << sqlite3_errmsg(db) << endl;
        return -1;
    }

    // 创建表
    char *zErrMsg = 0;
    rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS students (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)", NULL, 0, &zErrMsg);
    if (rc) {
        cerr << "Error creating table: " << zErrMsg << endl;
        sqlite3_free(zErrMsg);
        sqlite3_close(db);
        return -1;
    }

    // 插入数据
    sqlite3_stmt *stmt;
    rc = sqlite3_prepare_v2(db, "INSERT INTO students (name, age) VALUES (?, ?)", -1, &stmt, NULL);
    if (rc) {
        cerr << "Error preparing insert statement: " << sqlite3_errmsg(db) << endl;
        sqlite3_close(db);
        return -1;
    }
    
    // 插入多条数据
    for (int i = 0; i < 5; i++) {
        sqlite3_bind_text(stmt, 1, "Student " + to_string(i), -1, SQLITE_STATIC);
        sqlite3_bind_int(stmt, 2, 20 + i);
        sqlite3_step(stmt);
        sqlite3_reset(stmt);
    }
    sqlite3_finalize(stmt);

    // 查询数据
    stmt = nullptr;
    rc = sqlite3_prepare_v2(db, "SELECT * FROM students", -1, &stmt, NULL);
    if (rc) {
        cerr << "Error preparing select statement: " << sqlite3_errmsg(db) << endl;
        sqlite3_close(db);
        return -1;
    }
    
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        int id = sqlite3_column_int(stmt, 0);
        const char *name = sqlite3_column_text(stmt, 1);
        int age = sqlite3_column_int(stmt, 2);
        cout << "Record " << id << ": Name = " << name << ", Age = " << age << endl;
    }
    sqlite3_finalize(stmt);

    sqlite3_close(db);
    return 0;
}

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By running this program, a table named "students" can be created in the database named "students.db", which contains three columns: id, name and age. It also inserts five pieces of test data and queries the database to retrieve student information.

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