解决Oracle执行SQL报错SQL 错误 [12704] [72000]: ORA-12704: 字符集不匹配的问题

在Oracle数据库中，我有一条SQL需要执行，如下：

SELECT
	CASE
		WHEN "i"."CODE" LIKE '1%' THEN to_char('1')
		WHEN "i"."CODE" LIKE '2%' THEN to_char('2')
		WHEN "i"."CODE" LIKE '3%' THEN to_char('3')
		WHEN "i"."CODE" LIKE '4%' THEN to_char('4')
		ELSE "i"."CODE"
	END "CODE",
	sum("detail"."ZHEJJE") "leijzj"
FROM
			"FDW_DETAIL" "i"
LEFT JOIN "FDW_BASE_DETAIL" "detail" ON
			"i"."KEY" = "detail"."OBJ_ID"
GROUP BY
	"i"."CODE"

但是执行的时候会报错： org.jkiss.dbeaver.model.sql.DBSQLException: SQL 错误 [12704] [72000]: ORA-12704: 字符集不匹配
    at org.jkiss.dbeaver.model.impl.jdbc.exec.JDBCStatementImpl.executeStatement(JDBCStatementImpl.java:133)
    at