以下CASE 语句更新BET1、BET2、BET3 和BET4同时 ID=10。

$S1=32
$sql="UPDATE TIMER-BOARD1 
set BET1= case when BET1 IS NULL THEN $S1 else BET1 end ,
    BET2= case when BET2 IS NULL THEN $S1 else BET2 end,
    BET3= case when BET3 IS NULL THEN $S1  else BET3 end,
    BET4= case when BET4 IS NULL THEN $S1 else BET4 end
WHERE ID = 10";

当我运行 php 页面时，我有 BET1=32、BET2=32、BET3=32、BET4= 32。

我想要的是让脚本在找到并填充第一个 null 字段时退出。

即，以所有BET1、BET2、BET3、BET4 = NULL when ID =10开始，我希望在运行 php 页面时仅更新 BET1=32。当我再次运行它时，更新 BET2=32 等

类似下面的内容:

    $S1=32
    $sql="UPDATE TIMER-BOARD1 
    set BET1= case when BET1 IS NULL THEN $S1 
( EXIT AND DON’T BOTHER ABOUT OTHER CASE      STATEMENTS) else BET1 end ,
       BET2= case when BET2 IS NULL THEN $S1 
(EXIT AND DON’T BOTHER ABOUT OTHER CASE STATEMENTS) else BET2 end,
    BET3= case when BET3 IS NULL THEN $S1 
(EXIT AND DON’T BOTHER ABOUT OTHER CASE STATEMENTS)   else BET3 end,
    BET4= case when BET4 IS NULL THEN $S1 
(EXIT AND DON’T BOTHER ABOUT OTHER CASE STATEMENTS) else BET4 end
    WHERE ID = 10";

结果

Start values: ID=10 ,BET1=NULL, BET2=NULL, BET3=NULL, BET4=NULL.

Run the script 1ST time: ID=10, BET1=32, BET2 =NULL, BET3=NULL, BET4=NULL.

Run the script 2nd time: ID=10, BET1=32, BET2= 32, BET3=NULL, BET4 = NULL.

Run the script 3rd time: ID=10, BET1=32, BET2=32, BET3=32, BET4=NULL.

Run the script 4th time: ID=10, BET1=32, BET2=32, BET3=32, BET4=32.

Run the script 5th time or more: No null field, so no change.

如何编辑脚本来执行上述功能？

编辑

@伊诺斯赫奥

最后一个问题，如果你有时间的话。

在运行 sql 之前我有 $S1=32。假设我有 susan 而不是 32，这当然是一个字符串。

如何更新您的脚本以适应上述字符串？

$S1 =susan
UPDATE `TIMER-BOARD1`
set 
    ID = @UPDATED := 10,
    BET1 = case when BET1 IS NULL THEN @UPDATED:= susan else BET1 end,
    BET2 = case when @UPDATED = 10 AND BET2 IS NULL THEN @UPDATED:= susan else BET2     end,
…
    BET4 = case when @UPDATED = 10 AND BET4 IS NULL THEN @UPDATED:= susan else BET4 end
WHERE ID = 10;

谢谢。

最佳答案

您正在寻找“UPDATE first NULL column”。我认为这可以使用 MySQL 用户变量来实现。

你能试试这个吗？

架构和数据

DROP TABLE IF EXISTS `TIMER-BOARD1`;
CREATE TABLE `TIMER-BOARD1` (
  `ID` int(11) NOT NULL,
  `BET1` int(11) DEFAULT NULL,
  `BET2` int(11) DEFAULT NULL,
  `BET3` int(11) DEFAULT NULL,
  `BET4` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DELETE FROM `TIMER-BOARD1`;
INSERT INTO `TIMER-BOARD1` VALUES (10, NULL, NULL, NULL, NULL),
    (10, 32, NULL, NULL, NULL), (10, 1, 2, NULL, NULL),
    (10, 1, 2, 3, NULL), (10, 1, 2, 3, 4);

初始数据

SELECT * FROM `TIMER-BOARD1`;
+----+------+------+------+------+
| ID | BET1 | BET2 | BET3 | BET4 |
+----+------+------+------+------+
| 10 | NULL | NULL | NULL | NULL |
| 10 |   32 | NULL | NULL | NULL |
| 10 |    1 |    2 | NULL | NULL |
| 10 |    1 |    2 |    3 | NULL |
| 10 |    1 |    2 |    3 |    4 |
+----+------+------+------+------+

更新

UPDATE `TIMER-BOARD1`
set 
    ID = @UPDATED := 10, -- user defined variable which keep track WHETHERE CHANGED OR NOT
    BET1 = case when BET1 IS NULL THEN @UPDATED:= 32 else BET1 end,
    BET2 = case when @UPDATED = 10 AND BET2 IS NULL THEN @UPDATED:=32 else BET2 end,
    BET3 = case when @UPDATED = 10 AND BET3 IS NULL THEN @UPDATED:=32 else BET3 end,
    BET4 = case when @UPDATED = 10 AND BET4 IS NULL THEN @UPDATED:=32 else BET4 end
WHERE ID = 10;

更新数据

SELECT * FROM `TIMER-BOARD1`;
mysql> SELECT * FROM `TIMER-BOARD1`;
+----+------+------+------+------+
| ID | BET1 | BET2 | BET3 | BET4 |
+----+------+------+------+------+
| 10 |   32 | NULL | NULL | NULL |
| 10 |   32 |   32 | NULL | NULL |
| 10 |    1 |    2 |   32 | NULL |
| 10 |    1 |    2 |    3 |   32 |
| 10 |    1 |    2 |    3 |    4 |
+----+------+------+------+------+

问题

当你想更新 10 时仍然有问题。

已更新

1。使用一些 string_column

我想你有两个选择

1. 使用字符串列而不是 ID 列
   • 优点:可以使用一个更新来实现
   • 缺点:如果没有更多的字符串列则不能使用
2. 对每一行执行更新
   • 优点:即使没有更多的字符串列也可以使用
   • 缺点:执行多个UPDATE，没有PK就不能用。

我想知道你是否有一些像 string_col 这样的字符串列，如下所示。

架构和数据

DROP TABLE IF EXISTS tab;

CREATE TABLE tab (
  `ID` int(11) NOT NULL,
  `BET1` VARCHAR(100) DEFAULT NULL,
  `BET2` VARCHAR(100) DEFAULT NULL,
  `BET3` VARCHAR(100) DEFAULT NULL,
  `BET4` VARCHAR(100) DEFAULT NULL,
  `string_col` VARCHAR(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DELETE FROM tab;
INSERT INTO tab VALUES
    (10, NULL, NULL, NULL, NULL, 'A'),
    (10, 'Alice', NULL, NULL, NULL, 'B'),
    (10, 'Alice', 'Bob', NULL, NULL, 'C'),
    (10, 'Alice', 'Bob', 'Charlie', NULL, 'D'),
    (10, 'Alice', 'Bob', 'Charlie', 'Dave', 'E');

SELECT * FROM tab;
+----+-------+------+---------+------+------------+
| ID | BET1  | BET2 | BET3    | BET4 | string_col |
+----+-------+------+---------+------+------------+
| 10 | NULL  | NULL | NULL    | NULL | A          |
| 10 | Alice | NULL | NULL    | NULL | B          |
| 10 | Alice | Bob  | NULL    | NULL | C          |
| 10 | Alice | Bob  | Charlie | NULL | D          |
| 10 | Alice | Bob  | Charlie | Dave | E          |
+----+-------+------+---------+------+------------+

更新

UPDATE tab
set 
    string_col = @ORIG_STRING_COL := (@UPDATED := string_col),
    BET1 = IF(BET1 IS NULL, @UPDATED := 'Susan', BET1),
    BET2 = IF(@UPDATED != 'Susan' AND BET2 IS NULL, @UPDATED := 'Susan', BET2),
    BET3 = IF(@UPDATED != 'Susan' AND BET3 IS NULL, @UPDATED := 'Susan', BET3),
    BET4 = IF(@UPDATED != 'Susan' AND BET4 IS NULL, @UPDATED := 'Susan', BET4),
    string_col = @ORIG_STRING_COL
WHERE ID = 10;

结果

SELECT * FROM tab;
+----+-------+-------+---------+-------+------------+
| ID | BET1  | BET2  | BET3    | BET4  | string_col |
+----+-------+-------+---------+-------+------------+
| 10 | Susan | NULL  | NULL    | NULL  | A          |
| 10 | Alice | Susan | NULL    | NULL  | B          |
| 10 | Alice | Bob   | Susan   | NULL  | C          |
| 10 | Alice | Bob   | Charlie | Susan | D          |
| 10 | Alice | Bob   | Charlie | Dave  | E          |
+----+-------+-------+---------+-------+------------+

2。对每条记录执行一次UPDATE

用下面的伪代码，你可以实现它。

$res = mysqli_query(SELECT pk_column FROM tab WHERE ID = 10);

while ($row = mysqli_fetch_assoc($res))
{
    $pk_col = $row['pk_column'];

    mysqli_query("SET @UPDATED := ''");

    mysqli_query("UPDATE tab
        SET 
            BET1 = IF(BET1 IS NULL, @UPDATED := 'Susan', BET1),
            BET2 = IF(@UPDATED = '' AND BET2 IS NULL, @UPDATED := 'Susan', BET2),
            BET3 = IF(@UPDATED = '' AND BET3 IS NULL, @UPDATED := 'Susan', BET3),
            BET4 = IF(@UPDATED = '' AND BET4 IS NULL, @UPDATED := 'Susan', BET4)
        WHERE pk_col = $pk_column
    ");

}

前面的代码可以在客户端或存储过程中实现。

关于php - Sql-满足条件时退出CASE语句，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20608403/