您可以使用 RegEx 将逗号分隔的字符串解析为 MySQL 中的临时表吗?
'1|2|5|6' into temp table with 4 rows.
这与Can Mysql Split a column几乎是同一个问题?
MySQL 没有拆分字符串功能,因此您必须解决问题。使用上面答案页面上列出的方法之一拆分数据后,您可以对数据执行任何操作。
您可以遍历该自定义函数并在它返回空时中断,您必须玩并学习一些语法(或者至少我会),但是 mysql 中 FOR 循环的语法在这里: http://www.roseindia .net/sql/mysql-example/for.shtml
您可以对其进行迭代,增加以下函数中的位置:
CREATE FUNCTION SPLIT_STR(
x VARCHAR(255),
delim VARCHAR(12),
pos INT
)
RETURNS VARCHAR(255)
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
delim, '');
(来源:https ://blog.fedecarg.com/2009/02/22/mysql-split-string-function/ )
如果未找到匹配项,则应返回 '',因此如果未找到匹配项,则中断循环。这将允许您仅使用 mysql 解析拆分字符串并将插入查询运行到临时表中。但是人为什么不直接使用像 php 这样的脚本语言来完成这种工作呢?:(
循环语法代码:
DELIMITER $$
CREATE PROCEDURE ABC(fullstr)
BEGIN
DECLARE a INT Default 0 ;
DECLARE str VARCHAR(255);
simple_loop: LOOP
SET a=a+1;
SET str=SPLIT_STR(fullstr,"|",a);
IF str='' THEN
LEAVE simple_loop;
END IF;
#Do Inserts into temp table here with str going into the row
insert into my_temp_table values (str);
END LOOP simple_loop;
END $$
我找到了很好的解决方案
https://forums.mysql.com/read.php?10,635524,635529
感谢彼得布劳利
技巧:将 csv 字符串上的 Group_Concat() 结果按摩到 Insert...Values... 字符串中:
drop table if exists t;
create table t( txt text );
insert into t values('1,2,3,4,5,6,7,8,9');
drop temporary table if exists temp;
create temporary table temp( val char(255) );
set @sql = concat("insert into temp (val) values ('", replace(( select group_concat(distinct txt) as data from t), ",", "'),('"),"');");
prepare stmt1 from @sql;
execute stmt1;
select distinct(val) from temp;
+------+
| val |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
+------+
此外,如果您只想将某个表加入 id 列表,则可以使用 LIKE 运算符。有我的解决方案,我从博客文章 url 中获取 id 列表,将它们转换为逗号分隔的列表,以逗号开头和结尾,然后使用 LIKE 运算符通过 id 列表加入相关产品。
SELECT b2.id blog_id, b2.id_list, p.id
FROM (
SELECT b.id,b.text,
CONCAT(
",",
REPLACE(
EXTRACTVALUE(b.text,'//a/@id')
, " ", ","
)
,","
) AS id_list
FROM blog b
) b2
LEFT JOIN production p ON b2.id_list LIKE CONCAT('%,',p.id,',%')
HAVING b2.id_list != ''
DELIMITER $$
CREATE PROCEDURE SPLIT_VALUE_STRING()
BEGIN
SET @String = '1,22,333,444,5555,66666,777777';
SET @Occurrences = LENGTH(@String) - LENGTH(REPLACE(@String, ',', ''));
myloop: WHILE (@Occurrences > 0)
DO
SET @myValue = SUBSTRING_INDEX(@String, ',', 1);
IF (@myValue != '') THEN
/* my code... */
ELSE
LEAVE myloop;
END IF;
SET @Occurrences = LENGTH(@String) - LENGTH(REPLACE(@String, ',', ''));
IF (@occurrences = 0) THEN
LEAVE myloop;
END IF;
SET @String = SUBSTRING(@String,LENGTH(SUBSTRING_INDEX(@String, ',', 1))+2);
END WHILE;
END $$
我已经这样做了,因为当您没有表值等时:
select *
from(
select c, SUBSTRING_INDEX(SUBSTRING_INDEX('1|2|5|6', '|', c+1), '|', -1) as name
from(
SELECT (TWO_1.SeqValue + TWO_2.SeqValue + TWO_4.SeqValue + TWO_8.SeqValue + TWO_16.SeqValue + TWO_32.SeqValue) c
FROM (
SELECT 0 SeqValue UNION ALL SELECT 1 SeqValue) TWO_1
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 2 SeqValue) TWO_2
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 4 SeqValue) TWO_4
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 8 SeqValue) TWO_8
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 16 SeqValue) TWO_16
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 32 SeqValue) TWO_32
) as b
WHERE c <= (CHAR_LENGTH('1|2|5|6') - CHAR_LENGTH(REPLACE('1|2|5|6', '|', '')))
) as a;
可能不是最好的答案,但在没有函数和过程的帮助下工作,没有额外的表格等。
select distinct
SUBSTRING_INDEX(SUBSTRING_INDEX('1,2,3,4', ',', numbers.n), ',', -1) name
from
(select @rownum := @rownum + 1 as n
from YourTable
cross join (select @rownum := 0) r
) numbers
order by
n
您可以在 MySQL 中使用正则表达式来指定复杂搜索的模式,您无法解析字符串。
但是您可以在 REPLACE 和 CONCATENATE 的帮助下构建 INSERT 查询以将数据保存到临时表。
如果您尝试拆分的文本包含多字节字符,则此方法将因 LENGTH 计算不正确而失效。对于这种情况,使用 CHAR_LENGTH 而不是 LENGTH 的以下版本可以工作:
CREATE DEFINER=`root`@`localhost` FUNCTION `strSplit`(
`src` MEDIUMTEXT CHARACTER SET utf8,
`delim` VARCHAR(12),
`pos` INTEGER
)
RETURNS mediumtext
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE output MEDIUMTEXT CHARACTER SET utf8;
SET output = REPLACE(SUBSTRING(SUBSTRING_INDEX(src, delim, pos) ,
CHAR_LENGTH(SUBSTRING_INDEX(src, delim, pos - 1)) + 1) , delim , '');
IF output = '' THEN SET output = null; END IF;
RETURN output;
END
参考:http ://www.shakedos.com/2011/Nov/23/mysql-split-string-function-fix-split_str.html
只是因为我真的很喜欢复活旧问题:
CREATE PROCEDURE `SPLIT_LIST_STR`(IN `INISTR` TEXT CHARSET utf8mb4, IN `ENDSTR` TEXT CHARSET utf8mb4, IN `INPUTSTR` TEXT CHARSET utf8mb4, IN `SEPARATR` TEXT CHARSET utf8mb4)
BEGIN
SET @I = 1;
SET @SEP = SEPARATR;
SET @INI = INISTR;
SET @END = ENDSTR;
SET @VARSTR = REPLACE(REPLACE(INPUTSTR, @INI, ''), @END, '');
SET @N = FORMAT((LENGTH(@VARSTR)-LENGTH(REPLACE(@VARSTR, @SEP, '')))/LENGTH(@SEP), 0)+1;
CREATE TEMPORARY TABLE IF NOT EXISTS temp_table(P1 TEXT NULL);
label1: LOOP
SET @TEMP = SUBSTRING_INDEX(@VARSTR, @SEP, 1);
insert into temp_table (`P1`) SELECT @TEMP;
SET @I = @I + 1;
SET @VARSTR = REPLACE(@VARSTR, CONCAT(@TEMP, @SEP), '');
IF @N >= @I THEN
ITERATE label1;
END IF;
LEAVE label1;
END LOOP label1;
SELECT * FROM temp_table;
END
产生:
P1
1
2
3
4
使用时CALL SPLIT_LIST_STR('("', '")', '("1", "2", "3", "4")', '", "');
稍后我可能会弹出以使代码更潮一点!干杯!