生成100个10位随机数并保存到数据库

Question

This is a pretty simple function yet it keeps giving me errors. Im writing a script to generate 100 10-digit random numbers but I keep having this error: "check the manual that corresponds to your MySQL server version for the right syntax to use near 'rand(1111111111, 9999999999)' at line 1.

This is my code

<?php
$cxn = new mysqli("localhost", "CJroot", "password", "random");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
for ($i=0; $i < 100; $i++) { 
    $sql = "INSERT INTO random (random) VALUES 'rand(1111111111, 9999999999)'";
    if(!mysqli_query($cxn,$sql)) {
        die("Error: ".mysqli_error($cxn));
    }
}

/* close connection */
$cxn->close();
?>

Answer 1

您需要像这样连接字符串。

$sql = "INSERT INTO random (random) VALUES '" . rand(1111111111, 9999999999) . "'";

Answer 2

The syntax error that MySQL is complaining about (in your SQL statement) is missing parens around the values list. This is invalid:

INSERT INTO ... VALUES 'foo'

Should be

INSERT INTO ... VALUES ( 'foo' )
                       ^       ^

Once you get over that hump, the value enclosed in single quotes is interpreted as a string literal . In the example code, 'rand(11111,99999)' is a literal, a string of characters. It's not a reference to a function.

---

If we want to use the MySQL RAND() function, we could do something like this:

INSERT INTO random (random) VALUES ( FLOOR(1000000000 + RAND() * 9000000000) )

We can execute that 100 times, or, it would be more efficient to write SELECT statement that returns 100 rows, and insert 100 rows in a single insert.

Or:

INSERT INTO random (random) VALUES 
 ( FLOOR(1000000000 + RAND() * 9000000000) )
,( FLOOR(1000000000 + RAND() * 9000000000) )
,( FLOOR(1000000000 + RAND() * 9000000000) ) 
, ...
,( FLOOR(1000000000 + RAND() * 9000000000) ) 

---

In terms of database performance, it is usually more efficient to run a single INSERT statement that inserts 100 rows, than it is to execute 100 individual insert statements. Processing RBAR (row by agonizing row) can be excruciatingly slow.

If there's a need for a loop, if we insert four rows at time, we need only need to go through the loop 25 times. And that's 75% fewer statements we need to execute.

We can specify the SQL text to be executed just one time, outside of the loop, and then just repeatedly execute that same SQL

$sql = "INSERT INTO random (random) VALUES"
     . " ( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )";

for ($i=0; $i < 25; $i++) { 
  if(!mysqli_query($cxn,$sql)) {
    die("Error: ".mysqli_error($cxn));
  }
}

Answer 3

you can also do it direct with MySQL like this:

INSERT INTO random (random) 
SELECT CAST( (RAND()*(9999999999-1111111111)) AS UNSIGNED)  + 1111111111;

or for 100 rows:

INSERT INTO random (random)
SELECT  CAST( (RAND()*(9999999999-1111111111)) AS UNSIGNED)  + 1111111111 AS random FROM (
SELECT 0 AS h UNION SELECT 1  UNION SELECT 2  UNION SELECT 3  UNION SELECT 4  UNION SELECT 5  UNION SELECT 6  UNION SELECT 7  UNION SELECT 8  UNION SELECT 9 
) h
CROSS JOIN
( SELECT 0 AS l UNION SELECT 1  UNION SELECT 2  UNION SELECT 3  UNION SELECT 4  UNION SELECT 5  UNION SELECT 6  UNION SELECT 7  UNION SELECT 8  UNION SELECT 9 ) l;

Answer 4

This works fine

<?php
$cxn = new mysqli("localhost", "CJroot", "password", "random");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
$sql = "INSERT INTO random (random) VALUES"
     . " ( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )"
     . ",( FLOOR(1000000000 + RAND() * 9000000000) )";

for ($i=0; $i < 25; $i++) { 
  if(!mysqli_query($cxn,$sql)) {
    die("Error: ".mysqli_error($cxn));
  }
}
$cxn->close();
?>