DotNet,PHP,Java的数据库连接代码大全(带演示代码)

Posted 2020-09-26 sochishun

C#数据库连接字符串

Web.config文件

  <connectionStrings>
    <!--SQLServer数据库连接-->
    <add name="conn_test_sqlserver" connectionString="server=127.0.0.1;uid=testuser;pwd=testPwd;database=db_test;pooling=true;min pool size=10;max pool size=1024;connection lifetime=300;packet size=1000" providerName="System.Data.SqlClient"/>
    <!--mysql数据库连接-->
    <add name="conn_test_mysql" connectionString="Data Source=127.0.0.1; Database=db_test; User Id=testuser;Password=testPwd; pooling=false; CharSet=utf8; Port=3306" providerName="MySql.Data.MySqlClient"/>
    <!--SQLite数据库连接-->
    <add name="conn_test_sqlite" connectionString="Data Source=|DataDirectory|\\db_test.db3; Pooling=true; FailIfMissing=false" providerName="System.Data.SQLite" />
  </connectionStrings>
  <!-- 解决DbProviderFactories.GetFactory(ProviderName)出现的异常：“找不到请求的 .Net Framework Data Provider。可能没有安装。” -->
  <system.data>
    <DbProviderFactories>
      <remove invariant="System.Data.SQLite"/>
      <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".Net Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite, Version=1.0.105.2, Culture=neutral, PublicKeyToken=db937bc2d44ff139" />
      <remove invariant="MySQL Data Provider"/>
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.9.9.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
    </DbProviderFactories>
  </system.data>

示例代码：

protected void Page_Load(object sender, EventArgs e)
{
    try
    {
        object value = GetValue();
        Response.Write(null==value?"Null":value);
    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }
}
public object GetValue()
{
    string connName = "con_test_mysql";
    System.Configuration.ConnectionStringSettings connConf = System.Configuration.ConfigurationManager.ConnectionStrings[connName];
    DbFactory dbFactory = new DbFactory(connConf.ProviderName, connConf.ConnectionString);
    try
    {
        System.Data.Common.DbProviderFactory dbpf = System.Data.Common.DbProviderFactories.GetFactory(connConf.ProviderName);
        using (System.Data.Common.DbConnection conn = dbpf.CreateConnection())
        {
            conn.ConnectionString = connConf.ConnectionString;
            using (System.Data.Common.DbCommand cmd = conn.CreateCommand())
            {
                // cmd
                string sqlstmt = "select remark from t_user where account=@account";
                cmd.CommandText = sqlstmt;
                cmd.CommandTimeout = 30;
                // params
                System.Data.Common.DbParameter dbpara = cmd.CreateParameter();
                dbpara.ParameterName = "@account";
                dbpara.Value = "[e-mail]";
                dbpara.Size = 16;
                cmd.Parameters.Add(dbpara);
                // execute
                System.Data.Common.DbDataAdapter dbadp = dbpf.CreateDataAdapter();
                dbadp.SelectCommand = cmd;
                conn.Open();
                DataTable dtResult = new DataTable();
                dbadp.Fill(dtResult);
                object value = null;
                if (dtResult.Rows.Count > 0)
                {
                    value = dtResult.Rows[0][0];
                    if (DBNull.Value == value)
                    {
                        value = null;
                    }
                }
                return value;
            }
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

 

下载： CSharpDbConnectionDemo(DotNet数据库连接演示).zip

 

Java数据库连接字符串

// mysql
driver="com.mysql.jdbc.Driver";
url = "jdbc:mysql://localhost:3306/db_test?useUnicode=true&characterEncoding=UTF8";
conn = getConnection(driver,url, "user", "password");
System.out.println("与mysql数据库连接" + (null == conn ? "失败" : "成功"));
// sqlite        
driver="SQLite.JDBCDriver";
url = "jdbc:sqlite:/C:/db_test.db3";
conn = getConnection(driver,url);
System.out.println("与sqlite数据库连接" + (null == conn ? "失败" : "成功"));
// sqlserver        
driver="com.mysql.jdbc.Driver";
url = "jdbc:sqlserver://localhost:1433;DatabaseName=db_test";
conn = getConnection(driver,url, "user", "password");
System.out.println("与sql server数据库连接" + (null == conn ? "失败" : "成功"));
// oracle
driver="oracle.jdbc.driver.OracleDriver";
url = "jdbc:oracle:thin:@localhost:1521:orcl";
conn = getConnection(driver,url, "user", "password");
System.out.println("与oracle数据库连接" + (null == conn ? "失败" : "成功"));

JDBC连接数据库方法

public static Connection getConnection(String driver, String url, String user, String password) {
    Connection conn = null;
    try {
        //初始化驱动包     
        Class.forName(driver);
        conn = DriverManager.getConnection(url, user, password);

    } catch (Exception e) {
        e.printStackTrace();
    }
    return conn;
}

下载：[jdbc_connection_demo(JDBC连接各种数据库演示).zip]

 

php_PDO数据库连接字符串

// PDO连接MySQL的DSN字符串 (需要打开php配置文件中的"extension=php_pdo_mysql.dll"选项)
mysql:dbname=db_test;host=127.0.0.1;port=3306;charset=utf8
// PDO连接SQLite的DSN字符串 (需要打开php配置文件中的"extension=php_pdo_sqlite.dll"选项)
sqlite:test_db.db3
// PDO通过ODBC连接SQL Server的DSN字符串 (需要打开php配置文件中的"extension=php_pdo_odbc.dll"选项)
odbc:Driver={SQL Server};Server=127.0.0.1,1433;Database=db_test;
// PDO连接SQL Server的DSN字符串（配置非常麻烦，建议使用ODBC方式。PHP5.3.6以上的版本中php_mssql.dll，php_pdo_mssql.dll都已经不见了,只有一个php_pdo_odbc.dll,所以最新最好的php连接mssql方法应该是使用ODBC的驱动模式。）
sqlsrv:Database=db_test;Server=127.0.0.1,1433
// PDO连接PostgreSQL的DSN字符串 (需要打开php配置文件中的"extension=php_pdo_pgsql.dll"选项)
pgsql:dbname=db_test;host=127.0.0.1;port=5432
// PDO连接Oracle的DSN字符串 (需要打开php配置文件中的"extension=php_pdo_oci.dll"选项)
oci:dbname=//127.0.0.1:5432/db_test

示例代码：

$dsn = \'mysql:dbname=db_test;host=127.0.0.1;port=3306;charset=utf8\';
$pdo = new PDO($dsn, \'dbuser\', \'dbpwd\');
$stmt = $pdo->prepare(\'select id, name from t_user where user_name=:account\');
$stmt->bindParam(\':account\', $account);
$stmt->execute();
while ($row = $stmt->fetch()) {
    return $row;
}

 

/**
 * 查询并返回数组
 * <br />例如：
 * <br />query(\'select COLUMN_NAME, IS_NULLABLE, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, NUMERIC_SCALE, EXTRA, COLUMN_COMMENT from information_schema.columns WHERE TABLE_SCHEMA=:database AND TABLE_NAME=:table\', [\'database\' => $dbname, \'table\' => $tablename])
 * @param string $sqlstmt
 * @param array $params
 * @return array
 */
function query($sqlstmt, $params = []) {
    $dsn = \'mysql:host=127.0.0.1;port=3306;charset=utf8\';
    $pdo = new PDO($dsn, \'dbuser\', \'dbpwd\');
    $stmt = $pdo->prepare($sqlstmt);
    if ($params) {
        $names = array_keys($params);
        $values = array_values($params);
        $i = count($names) - 1;
        // 这里不能用foreach，参考bindParam陷阱(值参数是引用型变量)：http://www.laruence.com/2012/10/16/2831.html
        while ($i >= 0) {
            $stmt->bindParam($names[$i], $values[$i]);
            $i--;
        }
    }
    $stmt->execute();
    $out = [];
    while ($row = $stmt->fetch()) {
        $out[] = $row;
    }
    return $out;
}

 

下载：[pdo_dns_demo(PDO连接各种数据库演示).zip]

PHP官方DSN说明：http://php.net/manual/en/ref.pdo-odbc.connection.php
更多DSN连接字符串可以参考：http://www.connectionstrings.com/

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