MySQL将变量字符串参数传递给存储过程变量

Question

我有以下存储过程：

CREATE DEFINER=`sleuser`@`%` PROCEDURE `PCDD`(
in ProjectID int,
in MonthName varchar(50),
in ServiceCode varchar(50),
in ProjectName varchar(50)
)
BEGIN

SET @PCProjID = ProjectID;
SET @PCSN1 = "020." + ServiceCode + ".000";
SET @Month = MonthName;
SET @ImpCostID = ProjectName;
SET @ImpCostTask1 = "020." + ServiceCode + ".000";

SELECT 
project.project_id,
'FP' as Phase,
ImportCost.OriginalCommitments,
ImportCost.ApprovedCommitmentChanges,
sum(RegisteredChangeOrders) + sum(OriginalContractPrice) as CurrentAssigned, 
sum(ProjectCostBudget.PendingChangeOrders) as PendingScopeChanges,

FROM `RCLY-DEV`.ProjectCostBudget

inner join project on project.project_id = 
ProjectCostBudget.ProjectID
inner join ImportCost on ImportCost.ProjectID = project.pmis
where ImportCost.ProjectID = @ImpCostID and 
ImportCost.Task = @PCSN1  and  
ProjectCostBudget.ProjectID = @PCProjID and 
ProjectCostBudget.ServiceNumber = @ImpCostTask1

我称之为：

call PCDD(2,'September%2018','0000','RLCY-BB-01')

其中“ 0000”需要从“ 0000”到“ 6000”变化。当我为“ 0000”运行SP时，它返回预期的结果，但是当我将其更改为其他值时，它仅返回所有null。我尝试将@ PCSN1和@ ImpCostTask1更新为：

SET @PCSN1 = ("020.", ServiceCode, ".000");
SET @ImpCostTask1 = ("020.", ServiceCode, ".000");

但是我得到了错误

  

“操作数应包含1列。

我在这里做错了什么？为什么对一个ServiceCode无效，而对其他ServiceCode无效？

Answer 1

您需要使用' enqoute字符串文字和CONCAT而不是'+'来进行字符串连接：

SET @PCSN1 = "020." + ServiceCode + ".000";
=>
SET @PCSN1 = CONCAT('020.', ServiceCode, '.000');

相同于：

SET @ImpCostTask1 = "020." + ServiceCode + ".000";
=>
SET @ImpCostTask1  = CONCAT('020.', ServiceCode, '.000');