如何从我的PHP代码向MySQL存储过程获取NULL值？

Question

我在页面上有一张表格，里面充满了MySQL数据库中的值； 相当大的MySQL数据库。 我还对表的每一列都有过滤器，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内部调用它就可以。 但是，当我尝试从PHP代码发送NULL值时，在MySQL端会出现错误。 我在PHP端获取过滤器值，如下所示：

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

然后，我像这样调用存储过程：

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

就像我说的那样，唯一的问题是将NULL值从PHP页面获取到存储过程中。 如果我在MySQL内并使用以下查询，则会得到预期的结果：

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,,,,,,,,,,,,,,,,,,,,,,,)

我收到以下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

如您所见，没有NULL值，但是，我猜是要发送给存储过程的空值。 供参考，这是我的存储过程。 再次，我的存储过程可以正常运行，正如从MySQL内部期望的那样，但是从我的PHP页面调用时却不能。

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//

Answer 1

PHP“空”值与SQL空值完全不兼容。 插入字符串的PHP null只是一个空字符串。 例如

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

如果要将PHP null转换为SQL null，则需要将其设置为字符串'NULL' ，例如

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

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

并且您的SQL变为：

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