使用mysql分割字串 [英] Split strings using mysql
本文介绍了使用mysql分割字串的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想创建一个存储过程，它将对两个表进行匹配.我的要求是根据用户输入的列来匹配两个表.
I want to create a stored procedure which will do matching of two tables. My requirement is to match two tables based on the columns user passes as an input.
语法:
CREATE PROCEDURE reconcile.matchTables(
IN TAB1 VARCHAR(25),
IN TAB1 VARCHAR(25),
IN COLS1 VARCHAR(250) ,
IN COLS2 VARCHAR(250))
EX:
matchTables('table1', 'table2', 'col1#col2#col3#col4' , 'col2#col13#col1#col8')
现在，存储过程应该形成where子句，如下所示
Now the stored procedure should form the where clause like the following
table1.col1 = table2.col2
and table1.col2 = table2.col13
and table1.col3 = table2.col1
and table1.col4 = table2.col8
推荐答案
答案
表1
CREATE TABLE `Table1` (
`Col1` varchar(100) DEFAULT NULL,
`Col2` varchar(100) DEFAULT NULL,
`Col3` varchar(100) DEFAULT NULL,
`Col4` varchar(100) DEFAULT NULL,
`DummyColumn` varchar(45) DEFAULT NULL
)
表2
CREATE TABLE `Table2` (
`col2` varchar(100) DEFAULT NULL,
`col13` varchar(100) DEFAULT NULL,
`col1` varchar(100) DEFAULT NULL,
`col8` varchar(100) DEFAULT NULL
)
存储过程
CREATE DEFINER=`Connect7827`@`%` PROCEDURE `reconcile.matchTables`(
IN TAB1 VARCHAR(25),
IN TAB2 VARCHAR(25),
IN COLS1 VARCHAR(250) ,
IN COLS2 VARCHAR(250))
StartfromHere: BEGIN
DECLARE NoOfColumnInTable1 INT unsigned DEFAULT 0;
DECLARE NoOfColumnInTable2 INT unsigned DEFAULT 0;
Declare Column1Count int default 1;
Declare Column2Count int default 1;
Declare vPickOneValue varchar(100);
Declare querystring varchar(8000);
Declare NoOFRowsInFinalResult int default 1;
Declare _Tab1 varchar(1000);
Declare _TAB2 varchar(1000);
Declare _COLS1 varchar(1000);
Declare _COLS2 varchar(1000);
-- Column Names for Table 1
DROP TEMPORARY TABLE IF EXISTS Table1_Columns;
CREATE TEMPORARY TABLE Table1_Columns(Column_Name varchar(100));
SET @buffer= CONCAT_WS('','insert into Table1_Columns(Column_Name)
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = ',"'",TAB1,"'");
-- Select @buffer;
PREPARE stmt FROM @buffer;
EXECUTE stmt;
-- Column Names for Table 2
DROP TEMPORARY TABLE IF EXISTS Table2_Columns;
CREATE TEMPORARY TABLE Table2_Columns(Column_Name varchar(100));
SET @buffer= CONCAT_WS('','insert into Table2_Columns(Column_Name)
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = ',"'",TAB2,"'");
-- Select @buffer;
PREPARE stmt FROM @buffer;
EXECUTE stmt;
Set NoOfColumnInTable1=(Select count(*) from Table1_Columns);
Set NoOfColumnInTable2=(Select count(*) from Table2_Columns);
-- Select NoOfColumnInTable1,NoOfColumnInTable2;
if (NoOfColumnInTable1=0) then
Select 'Table 1 not found in database'as'Result';
leave StartfromHere;
end if;
if (NoOfColumnInTable2=0) then
Select 'Table 2 not found in database' as'Result' ;
leave StartfromHere;
end if;
IF (NoOfColumnInTable1!=NoOfColumnInTable2) then
Select 'No of column to be joined must be equal.'as'Result';
leave StartfromHere;
end if;
DROP TEMPORARY TABLE IF EXISTS BasedOn_Col1_List;
CREATE TEMPORARY TABLE BasedOn_Col1_List(ID int NOT NULL AUTO_INCREMENT, Column_Name varchar(100), PRIMARY KEY (id));
while Column1Count< NoOfColumnInTable1+1 do
set @Query=CONCAT_WS('' ,"insert into BasedOn_Col1_List(Column_Name) Select SUBSTRING_Index('",COLS1,"','#',",Column1Count,");");
-- Select @Query as'Value';
PREPARE stmt1 FROM @Query;
EXECUTE stmt1;
SET Column1Count=Column1Count+1;
end while;
SET Column1Count=1;
WHILE Column1Count<=NoOfColumnInTable1 do
SET vPickOneValue=(Select Concat(Column_Name,"#") from BasedOn_Col1_List where ID=Column1Count);
update BasedOn_Col1_List set Column_Name=replace(Column_Name,vPickOneValue,"") where ID<>Column1Count;
-- Select vPickOneValue;
SET Column1Count=Column1Count+1 ;
end while;
-- Preapre Table from Column2 Parameter
DROP TEMPORARY TABLE IF EXISTS BasedOn_Col2_List;
CREATE TEMPORARY TABLE BasedOn_Col2_List(ID int NOT NULL AUTO_INCREMENT, Column_Name varchar(100), PRIMARY KEY (id));
while Column2Count< NoOfColumnInTable2+1 do
set @Query=CONCAT_WS('' ,"insert into BasedOn_Col2_List(Column_Name) Select SUBSTRING_Index('",COLS2,"','#',",Column2Count,");");
-- Select @Query as'Value';
PREPARE stmt2 FROM @Query;
EXECUTE stmt2;
SET Column2Count=Column2Count+1;
end while;
SET Column2Count=1;
WHILE Column2Count<=NoOfColumnInTable2 do
SET vPickOneValue=(Select Concat(Column_Name,"#") from BasedOn_Col2_List where ID=Column2Count);
update BasedOn_Col2_List set Column_Name=replace(Column_Name,vPickOneValue,"") where ID<>Column2Count;
-- Select vPickOneValue;
SET Column2Count=Column2Count+1 ;
end while;
DROP TEMPORARY TABLE IF EXISTS TableFromColumnList;
CREATE TEMPORARY TABLE TableFromColumnList
( ID int NOT NULL AUTO_INCREMENT,
Table1Name varchar(100),
Column_Name_Table1 varchar(100),
Table2Name varchar(1000),
Column_Name_Table2 varchar(100),
PRIMARY KEY (id)
);
Insert into TableFromColumnList(Column_Name_Table1,Column_Name_Table2,Table1Name,Table2Name)
select t1.Column_Name,t2.Column_Name,TAB1,TAB2
from BasedOn_Col1_List t1 , BasedOn_Col2_List t2 where t1.Id=t2.id;
-- -- Preparing the final Result ----------------
While NoOFRowsInFinalResult<=NoOfColumnInTable2 do -- / Or NoOFRowsInFinalResult<=NoOfColumnInTable2 --
SET _Tab1 =(Select Table1Name from TableFromColumnList where Id=NoOFRowsInFinalResult);
SET _COLS1 =(Select Column_Name_Table1 from TableFromColumnList where Id=NoOFRowsInFinalResult);
SET _TAB2 =(Select Table2Name from TableFromColumnList where Id=NoOFRowsInFinalResult);
SET _COLS2 =(Select Column_Name_Table2 from TableFromColumnList where Id=NoOFRowsInFinalResult);
IF NoOFRowsInFinalResult=1 then
SET querystring =concat_ws("" , querystring,_Tab1,".", _COLS1 , "=",_Tab2,".", _COLS2," ");
else
SET querystring =concat_ws("" , querystring ,"and",_Tab1,".", _COLS1 , "=" ,_Tab2,".", _COLS2 ," ");
end if;
SET NoOFRowsInFinalResult=NoOFRowsInFinalResult+1 ;
End while;
SET querystring=concat_ws("","Select * from ",TAB1,", " ,TAB2," where ",querystring);
Select querystring;
END
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