如何从PHP代码到MySQL存储过程中获取空值？

我在一个页面上有一个表，我用MySQL数据库中的值填充它；相当大的MySQL数据库。我还为表的每一列设置了过滤器，以便用户可以过滤结果。我创建了一个存储过程，只要我从MySQL中调用它，它就可以工作。但是，当我试图从PHP代码中发送空值时，MySQL端会出现错误。我在PHP端得到的过滤器值如下：

$var01 = (isset($_GET['var01']) && $_GET['var01']) ? $_GET['var01'] : null;
.
.
.
$var23 = (isset($_GET['var23']) && $_GET['var23']) ? $_GET['var23'] : null;

$query = "CALL qyertWithFiltering (" . $var01 . ")"; // up to $var23

然后我调用我的存储过程，如下所示：

$var01 = (isset($_GET['var01']) && $_GET['var01']) ? $_GET['var01'] : null;
.
.
.
$var23 = (isset($_GET['var23']) && $_GET['var23']) ? $_GET['var23'] : null;

$query = "CALL qyertWithFiltering (" . $var01 . ")"; // up to $var23

唯一的问题是，正如我所说的，从PHP页面将空值获取到存储过程中。如果我在MySQL中并使用以下查询，我会得到预期的结果：

call query WithFiltering(10,1234,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);

但是，当我从PHP页面发送以下内容时：

CALL queryWithFiltering (10,1234,,,,,,,,,,,,,,,,,,,,,,,)

我得到以下MySQL错误：

Database Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ',,,,,,,,,,,,,,,,,,,,,)' at line 1

正如您所看到的，这里没有空值，相反，我想，我要发送给存储过程的是空值。作为参考，这里是我的存储过程。同样，我的存储过程工作得很好，正如在MySQL中所期望的那样，但在从PHP页面调用时却不行

use `my_database`;

DROP PROCEDURE IF EXISTS `queryWithFiltering`;

DELIMITER //
CREATE PROCEDURE `queryWithFiltering` (IN inLimit INT(11),IN inOffset INT(11),IN param01 VARCHAR(255),IN param02 VARCHAR(255),IN param03 DATE,IN param04 DATE,IN param05 DATE,IN param06 TINYINT(1),IN param07 INT(11),IN param08 INT(11),IN param09 INT(11),IN param10 INT(11),IN param11 DATE,IN param12 TINYINT(1),IN param13 VARCHAR(50),IN param14 VARCHAR(50),IN param15 DATE,IN param16 INT(11),IN param17 VARCHAR(50),IN param18 DECIMAL(13,2),IN param19 VARCHAR(50),IN param20 VARCHAR(50),IN param21 VARCHAR(50),IN param22 INT(11),IN param23 INT(11))
LANGUAGE SQL
DETERMINISTIC
SQL SECURITY DEFINER
COMMENT 'comment goes here ...'
BEGIN
DECLARE spLimit INT(11);
DECLARE spOffset INT(11);
DECLARE spVar01 VARCHAR(255);
DECLARE spVar02 VARCHAR(255);
DECLARE spVar03 DATE;
DECLARE spVar04 DATE;
DECLARE spVar05 DATE;
DECLARE spVar06 TINYINT(1);
DECLARE spVar07 INT(11);
DECLARE spVar08 INT(11);
DECLARE spVar09 INT(11);
DECLARE spVar10 INT(11);
DECLARE spVar11 DATE;
DECLARE spVar12 TINYINT(1);
DECLARE spVar13 VARCHAR(50);
DECLARE spVar14 VARCHAR(50);
DECLARE spVar15 DATE;
DECLARE spVar16 INT(11);
DECLARE spVar17 VARCHAR(50);
DECLARE spVar18 DECIMAL(13,2);
DECLARE spVar19 VARCHAR(50);
DECLARE spVar20 VARCHAR(50);
DECLARE spVar21 VARCHAR(50);
DECLARE spVar22 INT(11);
DECLARE spVar23 INT(11);

SET spLimit = inLimit;
SET spOffset = inOffset;
SET spVar01 = param01;
SET spVar02 = param02;
SET spVar03 = param03;
SET spVar04 = param04;
SET spVar05 = param05;
SET spVar06 = param06;
SET spVar07 = param07;
SET spVar08 = param08;
SET spVar09 = param09;
SET spVar10 = param10;
SET spVar11 = param11;
SET spVar12 = param12;
SET spVar13 = param13;
SET spVar14 = param14;
SET spVar15 = param15;
SET spVar16 = param16;
SET spVar17 = param17;
SET spVar18 = param18;
SET spVar19 = param19;
SET spVar20 = param20;
SET spVar21 = param21;
SET spVar22 = param22;
SET spVar23 = param23;

SET @primaryQuery = "select ... where ...";

IF (spVar01 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and alpha like '%", spVar01, "%'");
END IF;

IF (spVar02 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and beta like '%", spVar02, "%'");
END IF;

IF (spVar03 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and gamma like '%", spVar03, "%'");
END IF;

IF (spVar04 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and delta like  '%", spVar04, "%'");
END IF;

IF (spVar05 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and epsilon like  '%", spVar05, "%'");
END IF;

IF (spVar06 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and zeta =  '%", spVar06, "%'");
END IF;

IF (spVar07 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and eta like '%", spVar07, "%'");
END IF;

IF (spVar08 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and theta like '%", spVar08, "%'");
END IF;

IF (spVar09 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and iota like '%", spVar09, "%'");
END IF;

IF (spVar10 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and kappa like '%", spVar10, "%'");
END IF;

IF (spVar11 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and lambda like '%", spVar11, "%'");
END IF;

IF (spVar12 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and mu = '%", spVar12, "%'");
END IF;

IF (spVar13 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and nu like '%", spVar13, "%'");
END IF;

IF (spVar14 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and xi like '%", spVar14, "%'");
END IF;

IF (spVar15 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and omicron like '%", spVar15, "%'");
END IF;

IF (spVar16 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and pi like '%", spVar16, "%'");
END IF;

IF (spVar17 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and rho like '%", spVar17, "%'");
END IF;

IF (spVar18 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and sigma like '%", spVar18, "%'");
END IF;

IF (spVar19 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and tau like '%", spVar19, "%'");
END IF;

IF (spVar20 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and upsilon like '%", spVar20, "%'");
END IF;

IF (spVar21 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and phi like '%", spVar21, "%'");
END IF;

IF (spVar22 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and chi like '%", spVar22, "%'");
END IF;

IF (spVar23 IS NOT NULL) THEN
    SET @primaryQuery = CONCAT(@primaryQuery, " and psi like '%", spVar23, "%'");
END IF;

SET @primaryQuery = CONCAT(@primaryQuery, " order by ID limit ", spLimit, " offset ", spOffset);

PREPARE stmt FROM @primaryQuery;
EXECUTE stmt;

END//

PHP“null”值与SQL null值完全不兼容。插入到字符串中的PHP null只是一个空字符串。e、 g

$null = NULL;
$strin = "foo{$null}bar"; // comes "foobar", with nothing in between foo and bar.

如果希望将PHP null转换为SQL null，则需要将其转换为字符串

'null'

，例如

$phpnull = null;
$fakenull = "NULL"; //this is just a string that happens to say "null"

$sql = "UPDATE ... WHERE phpnull=$null, fakenull=$fakenull";

您的SQL变成：

UPDATE ... WHERE phpnull=, fakenull=NULL;
                         ^---empty string, because of PHP type conversions
                                    ^^^^^---php string, now being used as an SQL null