MySQL 中的 CRC32()函数

原文:https://www.geeksforgeeks.org/crc32-function-in-mysql/

MySQL 中的 CRC32() 函数用于计算循环冗余值。如果参数为空，则返回空值；否则，在计算冗余后，返回 32 位无符号值。

语法:

CRC32(expr)

参数: 此方法只接受一个参数。

  • expr–是要检索其 CRC32 值的字符串。

返回: 返回循环冗余值。

示例-1 : 使用 CRC32 函数查找字符串的循环冗余值。

SELECT CRC32('geeksforgeeks') 
AS CRC_Value;

输出:

循环冗余校验值
One hundred and fourteen million seventy-nine thousand one hundred and seventy-four

示例-2 : 使用 CRC32 函数查找数字的循环冗余值。

SELECT CRC32( 2020 ) 
AS CRC_Value;

输出:

循环冗余校验值
Two billion four hundred and ninety-three million eight hundred and four thousand one hundred and fifty-five

示例-3 : 使用 CRC32 函数为空参数查找循环冗余值。

SELECT CRC32(NULL) 
AS CRC_Value;

输出:

循环冗余校验值
空

示例-4 : 使用 CRC32 函数查找列数据的循环冗余值。为了演示，让我们创建一个名为 Player 的表。

CREATE TABLE Player
(
Player_id INT AUTO_INCREMENT,  
Player_name VARCHAR(100) NOT NULL,
Playing_team VARCHAR(20) NOT NULL,
PRIMARY KEY(Player_id )
);

现在，向播放器表中插入一些数据。

INSERT INTO  
Player(Player_name, Playing_team)
VALUES
('Virat Kohli', 'RCB' ),
('Rohit Sharma', 'MI' ),
('Dinesh Karthik', 'KKR'  ),
('Shreyash Iyer', 'DC'  ),
('David Warner', 'SRH' ),
('Steve Smith', 'RR'  ),
('Andre Russell', 'KKR' ),
('Jasprit Bumrah', 'MI' ),
('Risabh Panth', 'DC'  ) ;

所以，玩家表如下。

SELECT * FROM Player;

输出:

玩家 id 玩家名称 正在玩团队游戏
one 维拉·科尔 零售信贷局(Retail Credit Bureau)
Two 罗希特·夏尔马 大调音阶的第三音
three Dinesh Karthik KKR
four Shreyash Iyer 直流电
five 大卫·华纳 SRH
six 史蒂夫·史密斯 乡邮投递路线
seven 安德烈·拉塞尔 KKR
eight 贾斯帕·邦拉 大调音阶的第三音
nine 理纱波提 直流电

现在，我们将使用 CRC32 函数为 Player_name 和 Playing_team 列找到循环冗余值。

SELECT 
*, CRC32(Player_name),
CRC32(Playing_team)
FROM Player;

输出:

玩家 id 玩家名称 正在玩团队游戏 CRC32(玩家名称) CRC32(游戏 _ 团队)
one 维拉·科尔 零售信贷局(Retail Credit Bureau)  4234533515 Three billion five hundred and fifty-six million seven hundred and twelve thousand three hundred and seventy-four
Two 罗希特·夏尔马 大调音阶的第三音  2696911654 One hundred and eighty-five million five hundred and twenty-two thousand eight hundred and nineteen
three Dinesh Karthik KKR Seven hundred and three million three hundred and seven thousand eight hundred and thirty-two Three hundred and fifty-nine million thirteen thousand six hundred and sixty-nine
four Shreyash Iyer 直流电 Two billion eight hundred and seventeen million five hundred and forty-five thousand five hundred and ninety-three Nine hundred and seventy-four million seven hundred and fifty-one thousand nine hundred and fifty-six
five 大卫·华纳 SRH Three billion six hundred and forty-five million two hundred and fifty-six thousand and eighty-eight One billion six hundred and thirty million six hundred and fifty thousand two hundred and fifty-five
six 史蒂夫·史密斯 乡邮投递路线 Seven hundred and seventy-seven million two hundred and two thousand two hundred and fifty-seven One billion two hundred and seventy-eight million two hundred and eighty-seven thousand three hundred and forty-five
seven 安德烈·拉塞尔 KKR Three billion ninety million three hundred and six thousand six hundred and ninety-eight Three hundred and fifty-nine million thirteen thousand six hundred and sixty-nine
eight 贾斯帕·邦拉 大调音阶的第三音 One hundred and ninety-one million four hundred and sixty-one thousand and seventeen One hundred and eighty-five million five hundred and twenty-two thousand eight hundred and nineteen
nine 理纱波提 直流电 One hundred and seventy-eight million nine hundred and ninety-eight thousand six hundred and eight Nine hundred and seventy-four million seven hundred and fifty-one thousand nine hundred and fifty-six

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