sql示例：

SELECT
CASE
	
WHEN
	@CPDM != CPDM THEN
	@rownum := 1 ELSE @rownum := @rownum + 1 
END AS RN,
	@CPDM := CPDM AS CPDM,
	@BIZ_DATE := BIZ_DATE AS BIZ_DATE,
	a.QMRQ AS QMRQ 
FROM
	( SELECT @CPDM := '' FROM DUAL ) k,
	( SELECT @BIZ_DATE := '' FROM DUAL ) v,
	( SELECT @rownum := 0 ) r,
	(
	SELECT DISTINCT
		T.QMRQ,
		T.CPDM,
		T1.BIZ_DATE 
	FROM
		TC_PF_FISP003_CP_CPJZXX T
		LEFT JOIN ( SELECT BIZ_DATE FROM TC_DF_HOLIDAY C WHERE C.C_DATA_TYPE = 'CN' AND C.IS_HOLIDAY = '1' ) T1 ON T1.BIZ_DATE >= T.JZRQ 
	) A 
ORDER BY
	CPDM,
BIZ_DATE

sql在开发环境运行正常，但是在测试环境中运行时报错：

错误代码： 1267 Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_croatian_ci,IMPLICIT) for operation '='

经网上查资料，修改字符集测试后，发现问题所在。

问题原因：

        MySQL数据库有数据库的默认字符集，而数据库中的表字段也有自己的字符集。

问题解决办法：

修改表字段的数据集或修改数据库数据集。